I thought Adults showing sex to minors was illegal and yet MTV knowing that teens watch their channel, knowingingly shows TVshows where Sex is shown or implied even encouraged.

Why is the law people just let this go like it's nothing ?

MTV even tries to lure teens into their channel by having other interesting Real Life or whatever documentary shows that are good but then they mostly put other junk and Reality TV sex/or implied sex.

MTV is a cable channel. Don't like it? Don't pay for it or watch it.

I haven't watched MTV in over 20 years and my kids couldn't care less about it.

Cable TV is not as regulated as broadcast channels. Cable TV is subject to parental controls. So the only laws that might apply would be obscenity laws. And I doubt is MTV goes as far as to step over that line.