Yeah that’s a gross misunderstanding of what the purpose of a union is.
You do want a union even if you have good management.
A nice management might be able to give you a large salary, flexible worktime, etc.etc. all by themselves, but they’re still going to own you like a lap dog.
A union can give you the right to negotiate these things, so that you are free from being dependent on the handouts from the very nice management.
It’s not about taking control of the company or whatever they’re afraid of. It’s about taking control of your own employment and regaining your freedom and rights to have a say in it.