> The cynic in me thinks, if unions were such a bad thing, why wouldn't the owners let them form, burn the employees, and decertify?
Because unions gets more powerful than any company and can leverage said power against both workers and employers.
Lets take SAG-AFTRA as an example, a union many here at HN says the software industry should mimic. Their contracts with their workers states that the workers are not allowed to work at non-union shops, and their contracts with shops states that they are not allowed to work with non-union workers. This means that you as a worker has to join the union if your workplace unionize no matter if you feel it benefits you or not, and as long as the union control most workers any larger workplace will be forced to join or they will lack workers.
Why would workers not just stop being in the union, since it costs $3k to join and 2% of your salary to stay? Because the entire workforce at a union shop has to quit at once, at the same time the shop has to decide that they are not a union shop any longer. Do you think that will happen? No, of course not, weeding out a union in such a situation is way harder than starting the union in the first place. And even if they organize, the union could organize a picket in return to harass the shop and its worker into compliance.
Edit: Also PR and propaganda could easily make workers believe the union is good for them even if it isn't, kinda like how poor whites think that Republicans are on their side.