I don't know the details of the US programme, but London's recent successful scrappage scheme had a limit of £2000 for cars/vans and £1000 for motorcycles [1].
Only "dirty" vehicles that do not meet modern emissions standards qualified. And it only makes sense to scrap your vehicle if it's worth less than the £2000 payment you'd get by scrapping it. So nobody is scrapping modern, good quality vehicles: you'd just sell it instead and get more money.
Only "dirty" vehicles that do not meet modern emissions standards qualified. And it only makes sense to scrap your vehicle if it's worth less than the £2000 payment you'd get by scrapping it. So nobody is scrapping modern, good quality vehicles: you'd just sell it instead and get more money.
[1] https://tfl.gov.uk/modes/driving/ultra-low-emission-zone/scr...