But there's also lock-in. You only get the pension if you stay with a company. Through good times, and bad. maybe it's not a fun place to work anymore. Maybe it's downright horrid. But if you stay for another four years, you get your pension, so you stay.
Why is that good for employees? Wouldn't it be better to have fluidity (on the part of the workers) so that they can apply not just short-term pressure (strikes) but long-term pressure (retention)?
Or is this a situation where the structure of a union has incentives not aligned with the rank-and-file workers? (Because if you leave the company, you might fall under a different union representative, or a different union)