for children vs. for adults

Hay guys how come in Japan it's acceptable for adults to read manga but anime is strictly for children (or teenagers at most)?

It's really the same content, right? What the fuck difference does it make if I watch the Azumanga Daioh anime or read the manga? WTF. ZOMG.

No, seriously.

I'd say it's because adults don't watch much TV in Japan, they just work all the time. Kids watch TV there (lazy bastards), so anime on TV is targetted at kids. Of course, once the kids grow up, they stop watching TV too. Japan, thou art fucked up.