If you can get the car for a couple hundred, why would someone pay $1200?
Because that someone is impatient, impulsive, and has cash burning a hole in their pocket. Quite simple. Market meeting the demand.
Also, what is "clapped out"? Trashed? Worn out?
Worn out, not trashed. As in 25-30 y.o. engine that really hasn't been run much (think granny car), with seals going, various minor mechanical issues (steering pump not long for this world, that kind of stuff). Body and interior will be in fair shape for a 20-30 y.o. car, but basically it doesn't really make a good daily driver.
What, no bizarre paint job to seal the deal?
You get more money for the paint job.
Also works if there is a high concentration of those that hail from south of the border.
They seem to favor old Civics and even stuff like the old Ford Aerostar vans with $15 walmart rims and a wing on the top. Yes, I have seen that multiple times. IOW, they aren't quite as bling happy.