> Kids are smart and easily learn how to work around restrictions.

Absolutely. I feel like adults frequently mistake kids’ lack of education for stupidity. Lack of education about something is a temporary condition, and kids have ridiculous amounts of time, energy, and motivation to quickly become expert about something they care about. Particularly in reaction to “you can’t do that.”

One possibility: These laws forget that 18 year olds have kid siblings. The 18 year olds need money and like everyone else, enjoy the prospects of easy money. The 18-year-old has a phone bill to pay. These are the makings of a black market. Kid sibling acts as a broker for the older sibling’s services among the kid’s classmates and collect a commission.