Interestingly, (nearly) all of the Canadian government public servants are unionized. When you get hired, you can decide whether you wish to join the union or not, but the union will still collectively bargain on your behalf no matter what you choose.

The union is (mostly) in place to work on ensuring benefits such as sick leave, parental leave top-ups, overtime limits, etc. They also are there to ensure that management respects the rules when dealing with the workforce.