If that surprises you, I think you may need to do a little research about what unions are for.

They protect wages, working condition, and a way of life so the employee doesn't have to.  They can just do their job. That is their sole purpose.

They get a bad rep because of situations like this: if we were to take away per diem payments, it would be their legal obligation to fight that battle because it sets a legal precedent.  How hard they fight might be something different entirely.