> Doesn’t reading fiction require more imagination and active work than watching TV?

Theoretically, yes. But does this effort develop into skills useful in life? If not, then it's just entertainment.

> Personally, I think both are great! TV is fun to watch and there are lots of great shows. There are plenty of books with fun stories and characters.

I think so too! I love reading good fiction, and binding on good novel series just as much as I love binging on TV series! I just have issues with this popular notion that reading any book instead of watching TV makes you a smarter person, given that those books are usually light fiction, and not even something mind-expanding like e.g. some science fiction works.

> But does this effort develop into skills useful in life?

If you don't think that having an active imagination and being able to visualize a concept is a useful skill in life, then I don't know what else to say.

There's imagination, and there's imagination. I doubt novels will help you develop imagination the way e.g. solving spatial puzzles in your head will.

In my experience, prose doesn't force, or even encourage you to improve your imagination; it merely exercises your current levels. Kind of like opting for stairs instead of elevator when going up one floor - it doesn't really improve anything in your health, unless you're barely fit to walk, and is not a substitute for exercise that makes you reach the limits of your muscles.