system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Worker Unions.

I have never understand unions/employers during strikes, cause about contract negotiations. Employer offer new contract union rejects it. Why then employer can not disband(fire) employees(or let them continue to strike) and hire new union(workers) that are willing to agree to offered contract?
gpt
The company can do that.   The problem is that all the workers are united in order to strong-arm the company into meeting their demands.  

The company can totally fire them all and hire new workers who aren't part of that union.   However,  for skilled trades,  that means the entire staff needs to be trained ,  and all the guys who actually did the work are part of the Union and you just fired them,  so who is going to train these new dudes?
 
Even without that problem,  training the new staff or hiring that many people takes long enough that production  will decrease significantly,  likely costing the company much more money than just giving the  union workers the raise they asked for.