Now you need government permission to form a union?

The city of Seattle has just passed a law allowing drivers for services like Uber and Lyft to form a union.

Good.

But the real story here is pretty disturbing. Why did drivers need to have a new law passed to let them unionize? In my America, you didn't need a law like this. If you wanted to unionize, you could unionize. The right to unionize used to be already protected under other laws. I thought it still was. What happened?

Workers are being forced to beg cities to pass laws to give them rights that they already have under the Constitution?