Every single employee of every single company is in the best position they can have, unless they are stupid or insane. Otherwise, they would be working someplace else.
To agree to work under a certain set of parameters (wages, hours, working conditions), then say that those same parameters are unacceptable is immoral. If you think you can do better, GTFO.
Unions are institutionalized socialism, which doesn't work anywhere but in convents and monasteries. It discourages excellence and promotes laziness, dishing out rewards equally to the best and worst workers. There is a reason why less than ten percent of private sector workers in the U.S. are union members, and a reason why the American integrated steel industry is essentially dead, while the minimills (non-union) are doing fine. It is the same reason why all UAW car manufacturers have gone bankrupt (in fact, if not on paper), and all of the transplant auto makers in the US are doing fine.
Amazon and Starbucks will do everything legally possible to keep socialism out of their operations. It would be foolish of them to do otherwise.