I have a 12-pack of beer and bottle of vodka in my house. Does that mean that anyone under the age of 21 in my house can be charged MIP? Even if the 12-pack and bottle are sitting unopened?
LOL! I'd say you're safe. There are exceptions to the MIP laws, such as the minor being your own child, etc. that allow for such things as parents having a liquor cabinet with kids in the house. (Just don't make that liquor available to their friends.) Seriously.....These laws (IMHO) were written for parties. A neighbor calls and says, "Hey, the Jacksons are supposed to be out of town, but there are 30 cars parked on our street, kids going in and out of that house and loud music is playing. I want you to come check it out." In 99% of the cases, there will be alcohol involved. In some instances, the Jacksons aren't out of town and are the sort of parents who want "the drinking to go on at our house instead of somewhere else," so they make it alcohol available to minors, even those who aren't their kids. Then the Jacksons have to face serious charges, idiots that they are.

Sometimes I think it ought to be called the MAP (Minors at Party) law instead of the MIP law.
What happened to the OP is exactly what I was speaking of......Enforcement is very "jurisdictional." In this case, two minors got two different judges and the minor who was a repeat offender actually received a much lighter sentence than the first time offender. Where I worked, that wouldn't have happened simply because we didn't split up cases between judges, but instead had a "cattle call" and handled all the related cases (if possible) on the same day, with the same small group of prosecutors and one judge. We worked out plea bargains in the conference room, presented them to the judge and she signed off. We wouldn't have offered a better deal to a repeat offender than a first timer. But that's another reason a local attorney who is VERY familiar with these cases can be very useful. That attorney might know that going before Judge A is a positive thing, but seeing Judge B can be a disaster.
When I first moved here, I was stunned at how one judge conducted his courtroom. Blatant violations of the law and he bullied every lawyer in there, to say nothing of the defendants. Just a month ago, I finally added 2 + 2 regarding him. About 15 years ago, before we moved here, there was a famous Texas case involving a claim of wrongful conviction in a capital murder case. I knew something about it, but not THAT much of the finer details. I did know that sometime after we moved here, the man was indeed set free. (Local guy.) Anyway, about a month ago, I was watching some crime show and it featured the case. I heard the guy's name and realized it was THIS county, so I decided to watch. The lead-in was about a crooked judge who did whatever he pleased.
Lo and behold, it tirned out to be THAT judge. I had never realized HE was the judge in the case. I told DH that considering that judge had no regard for the rules and made it up as he went along to please himself, I had no doubt that everything they said was true, especially since his own staff testified to that effect. I told DH I'd never seen anything like him on the bench, but to watch the show now that I
KNEW what he was really like put the case in a whole new light. For years, I'd said, "God help the defendant that goes before him," (and I'm pro-prosecution

) because their rights meant nothing, but sending a man to death row by shady means was the lowest.