My own experience working in a white-collar union with a just cause provision is that the process is much more cumbersome and time consuming, and includes some

My own experience working in a white-collar union with a just cause provision is that the process is much more cumbersome and time consuming, and includes some off-ramps, but it is certainly possible to fire and or punish low performers. The more concretely "low performance" can be measured, the quicker and easier, but we're still talking months or years.