This is the good old, but ultimately petty, Pyrrhic victory of wanting to make sure to punish the few freeloaders.
I'm open to a system that allows all of these things to happen.
However - applying that system on a micro scale (one workplace at a time, through unions) introduces way too much friction between employers and their employees, employees and their peers, and employers and unions.
It also causes an internal conflict for the employee - where they have to mask their lack of contribution by busywork, ultimately feeling unfulfilled in their life.
Unionizing all workplaces is a sub-optimal means to distribute wealth.