Broadly I see what you're saying and agree with you. When it is more efficient to produce a new thing on an assembly line than fix it, we actually all benefit. But knowing where that crossover is is tough. You can't use the same rule for everything.
The worst case of throwaway was the 'cash for clunkers' scheme. That saw wholesale destruction of large amounts of serviceable vehicles, with replacements being created on production lines. It was wealth destruction all around and benefited nobody but a couple of car salesmen who got better comission checks that month.
And air quality, and road safety. That kind of scheme is an incentive to lower the externalities of motoring - older cars burn more fuel, produce more pollution, and have less safety features.
And drove the price of used cars through the roof. A car that might have run you $100 twenty years ago ("drive it until it's dead") will now run you a cool kilobuck - granted, the high value of scrap (a Geo Metro is worth about $300 locally at a scrap yard) - if you can find a bargain. Here's a 19 year old car that the owner is asking $2300 for: http://kansascity.craigslist.org/cto/3003688305.html
Indeed - and it goes much further than just the prices in regional USA or Europe.
Some guy in Africa will be wondering why his cab fares mysteriously went up, and will have no idea that it was a vote-buying scheme halfway across the world in a country he'll never visit.
Some of the cars scrapped were worth several thousand, and would have lasted for years, both as serviceable vehicles and donor vehicles to keep others on the road. But they were forcibly destroyed and scrapped, taking all their parts with them.
The scheme, in all its incarnations around the world, was stupid and destructive.
Jeremy Clarkson summed it up best with his quip 'we'd be better off giving everyone in the Taliban a decent used car if they promised to stop shooting at us'.
I'm not in the US. Over here, the idea of a car worth driving costing only 100 euros is ludicrous, and was so even before the local scrappage schemes took plenty of 10-years-or-older cars off the road.
(100 euro cars used to be found; people who don't want to admit their car's worth nothing. They were often bought by teenagers, driven psychotically for a night, and burnt out. These days I assume they're being driven into the ground instead.)
A car that cheap here isn't expected to last long, either, but some of them do. You might have a door wired shut, the windows may not work, the air conditioning, if the car had any to begin with, doesn't work, and it might be loud. But it's a car, and they're near-essential in the USA, thanks to our lousy transportation and sprawl-encouraging policies.
Road safety is a maybe, air quality is a theoretical as the numbers are so low. Contrary to popular belief, most of the cars weren't 70's gas guzzlers but late '90s models with relatively efficient fuel injected engines.
The energy used to create and deliver the new cars far exceeds the energy used to continue using the old ones.
There is no defending this insane scheme unless you want to get into partisan politics and go for the symbolism of it.
Knock yourself out; I'm not in the US, I don't even know which side proposed it. I was just pointing out some benefits other than increased commissions, ones that could be observed from the scrappage scheme we had a few years ago.
The worst case of throwaway was the 'cash for clunkers' scheme. That saw wholesale destruction of large amounts of serviceable vehicles, with replacements being created on production lines. It was wealth destruction all around and benefited nobody but a couple of car salesmen who got better comission checks that month.