I'm very pro union. But not all unions are good. My father's union is so bad he might actually be losing money. They just roll over for management to fuck them, barely negotiate anything at all. Last time, they 'negotiated' an increase in pay, and the increase was actually SMALLER than the increase in union dues.
Oh, and they only defend the worst of the worst. Litteral thief, stealing, caught on camera, multiple times ? Well defend you tooth and nails. 'Til the management litterally had to get police involved for them to back down.
Unions in general are good. But for some specific unions, ymmv.
When it's a low amount in theft, it's more trouble involving police than just letting them go. It's also on their record, barring them for future job and putting in legal problem
So it's better for everyone involved. Unless union want to literally defend a thief