flaking paint???

hi, all. I have a 2004 passat glx, bought recently certified pre-owned.
I live in D.C. and must park on the street. with my old car (a 1996
eagle talon), I could see places in the paint on the bumpers where
folks bumped into my car while parking. the hazards of parking in the
city. there were scratches and whatnot, but nothing major.

but, with my passat, the paint is literally flaking off the bumper.
I've been using touch-up paint on some of the scuffs. but now someone
bumped my car fairly hard, causing a 4-inch crack in the paint that's
flaking. what's going on???

anyone else experiencing this? and, does anyone know if/how I can use
touch-up paint on flaking that big? any advice?

thanks!