Some of the largest unions in the world are for teachers, police, and government employees. I’m not sure why you would think a for-profit company is uniquely subject to its staff unionizing?

I have similar questions about public service unions as well. The reason why it makes sense to me for private for-profit companies is because stakeholders have a profit incentive to exploit workers. If non-profit tech workers are especially vulnerable to exploitation, then I guess it makes sense too, but I'm having trouble finding evidence for that.