Depends on the instructor. While many North American-trained instructors are pushing the sport rather than the martial art, there are still true practitioners out there, usually older Korean men who are first-generation immigrants.

The Grandmaster from whom I learned was a South Korean army instructor first, and he never forgot it. While the kids' classes still focused on the fun, the advanced adult classes were a whole different animal. Bruises and the occasional bloody nose and loosened tooth were teaching tools, and "light contact" could mean anything short of broken ribs.

I got knocked around (when others' control slipped), knocked people around (when mine was lacking) and learned that getting hit hard really doesn't hurt until later.

TKD does lack a close-combat function, but most Grandmasters know hapkido (borrowed aikido that is much less pretty and focuses on crippling rather than submission) and a lot of them have a bit of judo as well. I'd love to find a good judo instructor, but it's hard in a rural area.