When I was a kid it would have been pretty unusual to let a kid have a TV in their room. Some parents did it, but it was never seen as appropriate. This was the 1980s to 1990s. Now we make sure everyone has much, much more than a TV on them at all time. It's a huge cultural shift in itself and has not been a healthy one.
It wasn't inappropriate, it's just that you typically didn't have multiple cable boxes. There wasn't really a reason to have a TV in a kids room if you're only getting OTA broadcasting, there wasn't much for kids other than like Saturday morning cartoons. I knew plenty of kids in the 90s with a video game console and TV in their room though. It was for games, not TV watching.