Not really, if you're drinking inside your home a cop can't invade your house without probable cause, and unless you're loud and unruly that's hard to find.
It's still illegal. Just because your in your home doesn't mean it's not. The legal drinking age is 21, no exceptions. Just because there is a lesser chance of getting caught doesn't mean it's not illegal.
If you're at a party and there is under-age drinking and the cops DO come into your home, and they find out what's going on, someone's going to jail.