> I've always wondered what their ultimate collective bargaining power
To be fair, unions don't exist solely as threats to employers. The ability to bargain collectively still results in better/fairer outcomes in most situations. Most of the time, employers want to compensate their employees in good faith. Most of the time, employees want to work for a team who get rewarded more or less fairly and not compete in a cutthroat arena where everyone has to bargain for themselves.
But yes: non-striking unions are absolutely not going to have the kind of corrective power in the face of genuine imbalance that real organized labor does.
To be fair, unions don't exist solely as threats to employers. The ability to bargain collectively still results in better/fairer outcomes in most situations. Most of the time, employers want to compensate their employees in good faith. Most of the time, employees want to work for a team who get rewarded more or less fairly and not compete in a cutthroat arena where everyone has to bargain for themselves.
But yes: non-striking unions are absolutely not going to have the kind of corrective power in the face of genuine imbalance that real organized labor does.