if I owned a beautiful new convertible, I'd much rather see it on a winding mountain road or in a field somewhere.
Me, too. And the open spaces allow the contours of the body to be defined by the highlights from the sky. The "alley with graffiti" would have it's place, as in this thread where I suggested it instead of the background that was used, which would be better for a working truck, but I'd still expect some care being taken to get some good reflections in the body.
Some are stuck in the mindset that a cool background makes for a great shot of the subject. To me, a background is just that...background. The best choice for me is one that doesn't take attention away from the car. If the background looks good in the process, then that's a bonus. But the first objective should be to make the car look good. I got a lot of flak from that over my comments on #1 in this thread. Great background. Great car. Crappy image of the car which looks like it was painted with flat red paint.
or is it big city young people just photographing cars in their neighborhoods...
Some of it seems to be that they just don't understand what it takes to make a car look good.
Some is just laziness. How many threads start out with, "Just a quick shot...", "I didn't have time...", "I liked the location...", yaddayadda... How many times has someone said, "I didn't have time to turn the wheels"? 
Some of it is being "in the moment" & just wanting to share, which is fine. As I said at the beginning of the "Tips" thread, "As in anything else, there's no one way to take a good looking shot of a car. Some guys like grungy garage pics. Others put it in 20% of the frame in what looks more like a landscape shot. Neither are "Wrong" if you get the results that you wanted, but I'd still like to see one shot in a series that makes the car/bike/etc. look as good as possible."
Shooting cars at meets where we can't move them is a different situation. But we can still take the time to try to find the best angle for them. And if we take the time to do a little "social engineering", maybe we can get it moved to a better spot to shoot from: '33 Ford Pro-Street 3 Window Coupe