Pasadena, CA? That's where I did my undergrad.

And in fact, during that undergrad time (before I got properly into bikes), I rode a real piece of garbage from Target (a Magna Glacier Point) whose handlebars also came loose despite tightening them down. Such is the way of cheap components. Properly made stems and bars don't do things like that.

My solution was to reinstall the bars as well as I could, drill a hole through the handlebar and the stem, tap the hole, and put a machine screw through both components.

That solution got me through undergrad. That bike injured me twice before I graduated, but both times it was from other failures than the stem/bar interface (if I remember the failures were the seatpost and the stem/steerer interface).

Sorry to be so grim, but I really get mad when I think of things that are so shoddily made yet so important for personal safety.