I don't know enough about the US, but for Europe this is 100% false! The first unions date back to the 18th century and they were an important part of the worker's movement in the 19th century. They absolutely played a crucial part in improving worker conditions during the industrial revolution and beyond.

> Jobs get nice when employers are competing over the same pool of employees.

Maybe in high-paying jobs that require high qualifications. For most jobs, especially the low-wage sector, this is absolutely not the case. There is no competition between employees if applicants are desperate and need to take any job they can.