Meanwhile I actually started college at 16 which is illegal in some locales.
In the US or elsewhere? I've known a lot of people who attended college at 16, and through friends with teenage children know even more these days. They attended (or are attending) schools in a variety of states.
But which states? I haven't been able to find anything about states barring minors from attending universities.
https://www.vccs.edu/application-information/
To qualify for general admission to a college, you must have a high school diploma, its equivalent, or be 18 years of age or older.
Unclear whether that is statewide or just a requirement of this state institution. I suspect many of the ones that do have this age requirement also have the diploma exception.