Most people instead buy pre-hung doors.

Bad example against reparation i.m.o. since when the hinge break they don’t buy a new door(whole), but swap the broken hinge(part) for a new one.
Good example in the case of DIY though, since the hassle may not be worth the time spent.

most components can’t be so easily replaced.

Every module in my computer, mouse, keyboard, screen, or, i.d.k., lamp torch, can be easily replaced with a screwdriver.
Even phones could be made easy to open. If you have a counter-example in mind to « unless when the part is difficult to access, which doesn’t seem to be an engineering necessity in most cases ? » written above, then i’m interested.

Even if you have access to spare parts, it takes a lot of time to repair something even as simple as a radio.

But opening it and swapping the spare part(, well, welding it back then,) took less than 5mns.
What took a long time was opening it without breaking anything since it was fragile, with parts glued together. Radios were more complex than nowadays.
And they didn’t stop at swapping the spare part apparently, but ran a full diagnostic because other parts aged as well and, e.g., a shorted transistor could overheat a transformer.
To me, it seems like asking for an individual to repair his watch himself by getting a spare part, these are the kind of situations that should be done by pros. But then even if it takes many hours we’re not talking about a 20€ product, so it’s usually worth it to repair instead of buying a new one(, which is why people repaired them instead of buying new ones).
Other examples could include houses or cars, which are repaired because buying new ones wouldn’t be worth it.

But the example of the radio still goes in my direction, because back then it was difficult to swap the spare parts and yet people still went through the trouble of repairing it.
How much more would it then be pertinent for objects that are thrown away while a pro could easily swap the spare part in 5mns(, or an individual do it h·er·im·self).
The problem i.m.o. is that there’s no repair·wo·man and no spare parts at a cheap price with close warehouses, so it’s not profitable/widespread.
You’re saying that most objects couldn’t have their parts easily swapped while i’m saying that most could(, at least we agree that some can&can’t)

Unless you can automate the entire repair process, increased automation will make us more likely to throw things away.

I also disagree that more human labor would be required to swap a part than to build the whole product 🤷
I even think that less human labor would be required to swap a part than to build it.
Many humans are involved with the production process, from mining to selling.
And if you were thinking in terms of advanced robots taking human jobs, then they’d eventually be able to do simple reparation as well(, and more&more complex over time).
(Edit : and if we could have said that «this automaton will create 150 circuit boards of this particular model every model, while the previous generation only made 50/h», we can also say that «this automaton will create 150 different kind of circuit board, while the previous generation could only create 50», if that’s part of the counter-argument)

And worse, automation makes it easier just to start from scratch.

Not easier to build the whole than the part

You can always take a broken device, throw it in a crucible with a mountain of other broken devices, and just melt the whole lot down.

Not really :)
But you could strip its parts yes, that’d be the most sensical option if you can’t repair it.

Sure, i’m optimistic(, but it’d make so much more sense than throwing away)

It’s always going to be easier to automate the production of goods than the repair of goods.

We can automate the production of spare parts.
And swapping a part for another is quick and can usually be done by the consumer(, or by a pro if it’s more complex).
Repairing a part is hard, but swapping it is usually easy, unless when the part is difficult to access which doesn’t seem to be an engineering necessity in most cases ?

I looked into buying a DIY kit for making a mouse recently in order to easily repair it(, and eventually improve/customize it i.d.k., at least understand it better), but there’s not much choice so i gave up and bought one at 30€.

you often find it is made of parts you can replace

But good luck to find these parts, they have a serial number but from my experience with a computer screen, the circuit board is really expensive and takes a long time to ship, so they told me to just buy a new screen(, it was only one of its ~4 circuit boards, and a small component of it furthemore, but everything was thrown out).
That’s probably why most objects are just thrown away and people don’t even attempt to repair them(, if it was cheaper that practice would probably be more widespread)

I have repaired my computer mouse recently

You opened it and found a spare part online for a cheap enough price ?
It must be a big(&unusual?) brand if they sell parts for their mouse online.

now they’re like over $200

I’d have to look at the specs to see if the difference with a $40 mouse is worth paying 5 times more 🤷

Wow

It also reminds me that it was apparently cheaper to destroy most of the military equipment when leaving Afghanistan than rapatriating it.

Industry and automation made production way more cost efficient

It should still be cheaper to build a new part(, and change that part,) than a new whole(, and buy that whole).

And i.d.k. if it’s the only reason for the low prices : it’s cheaper for westerners to buy from non-westerners(, including mines or actions), and conversely.
Repairing is done locally(, otherwise the transport would take too long), and ends up being more expensive than buying new products made externally.
Our productivity may be higher[1], even if we’re deindustrialized, but their minimum wage is way less than ours.
[1] : I.m.o., even more obviously when considering that we’re in the finance sector, we may reverse things when saying that a high productivity explains the difference in living standards : it’s the difference in living standards and GDP that inflates the productivity.
Since productivity∝GDP, then countries with a high GDP will have a high productivity.
And a country that increased its GDP(, e.g. through increasing its minimum wage perhaps,) would hence increase its productivity. Just an uninformed thought on my part, i.d.k. honestly.

If i keep the example of the computer mouse, it couldn’t cost 20€ if it was produced locally, if only because it takes much more than 2 cumulated hours to build one, at a minimum wage of 10€/h.
Conversely though, it’d mean that it’d be very expensive for a non-westerner to buy products made in the west, which is the case, but we can still manage to sell them because we have a monopoly on new technologies(, with e.g. Japan or South Korea, but then again their minimum wage is high as well so it’s the same remark), such as planes or softwares.

Who knows, 50 years ?

I don’t think we’ll continue like that, it can’t make sense for too long that buying a new one is cheaper than repairing an old one.
I suppose.