Getting fined by the union for moonlighting without permission.
Eventually get kicked out of the union for working to feed your family- thus losing your primary job and and subsequent secondary. Now you're a dickhead parent who won't feed their family, because- politics.
Unions are great when they work- crap when they don't. Gotta pick your own battles when it comes to that one.
and none of them have any issues at all with more than one job, and I guess when you cover a broad industry that's to be expected