HR is generally seen as being anti-employee, in the sense that the reason they exist is to protect the company (legally speaking) by managing its relationships, benefits, compensation, etc., with employees, and this often pits the company's interests against those of the employees.

It's quite silly for anyone to see HR this way in the first place. They get paid by the employer. Union execs get paid by employees. Figure out which is pro employee.

Human Resources mean managing the resources that are humans. Not resources for humans.

HR is there for the company.

Depends on which union, really. Corruption is a real problem in some of them, and in others the will to fight is weak or state laws make them much less powerful.

I don't know a lot about the mechanics of unions, but are the salaries not paid out of employee dues?