That has nothing to do with unions though, obviously. If you look at any organisation you tend to see people who have been there a long time without moving upwards or onwards are pretty lazy people who know how to play the system. They don't need a union for that.

A lot of people who are anti-unions appear to think the union is the cause of everything bad without noticing the same things happen everywhere else as well. Keeping shitty staff around is much more a function of employers who don't track how good their staff are than anything to do with unionization.

Also, forming an opinion about unions based on one job that lasted 3 months with 10 co-workers, the majority of who were hard-workers, is appalling. That isn't anywhere near enough information. You really need to try harder.