You're recommending everyone unionize, even though some unions are shitty and may end up being a net negative for people. But, aren't some businesses or sectors not shitty? Why unionize in nonshitty sectors or businesses?
Unionizing in a non-shitty sector will give the workers a way to help ensure that the sector continues to not be shitty, both by maintaining a baseline for what a union shop looks like, and by contributing money to politicians who will work to pass laws that help keep the sector free of shittiness.
But the sector is already doing a good job of being non-shitty without a union. And what about the case where you're in a non-shitty sector, but end up with a shitty union, resulting in a net negative for the employees? Do you just say "Oh well, it was for the greater good. Someone else somewhere has a union which is non-shitty, just in case some day the sector becomes antagonistic with employees"?
> You can always unionize later. Ununionizing might be a much bigger challenge.
Deauthorization of a union is much more difficult than forming a union in the first place. It is very difficult to obtain sufficient support for deauthorization without the union leadership hearing about it, at which point they can usually find sufficient reason to expel the member from the union. If there is an exclusive contract with the employer (which is usually the case in the US), this may result in the employee's termination.
Even if there is enough support for deauthorization to require an election, the NLRB has the authority to overturn the results of the election, and it has historically wielded this power quite generously in favor of the union.
It seems prudent to unionize and protect yourself while the business/sector is employee-friendly rather than have to unionize if the employer is taken over etc.