It really seems like you do mean to make this political. GP was talking about accusations of Tesla doing something illegal. You came in and brought up political

It really seems like you do mean to make this political. GP was talking about accusations of Tesla doing something illegal. You came in and brought up political parties and the value of unions, making the discussion much more political. To answer your question, obviously there are both pros and cons to unions (as with basically all political issues). If unionization costs jobs, and the left considers unionization a victory, it must mean that they value the other benefits gained from unionization (e.g. improved working conditions) more than the jobs lost from it.