Unions don’t protect the general public against a company. They protect the ranking members of a company.
That means the union also protects members of the company from the general public who might be looking to take their job by offering to work harder or better or cheaper.
If you’re a young person getting started in this industry it might be fun to imagine working in a unionized environment, but remember that the union would be working to protect its members from you breaking into the company and entering the senior ranks.