I agree that Unions have a lot less power today.
We also have so many laws in place to protect people "sexual harassment" "bullying" so you have rights even without having to have a Union Rep.
The union rep if any good will be able to explain these regulations clearly and give advice when the regulations have been broken by employee or employer.
everything is in black and white in the rule books so if the line is crossed they can remove a person - no problem
This is another area where a good rep can help, If you get a written warning for one "offence" a second for an other doesnt equal dismissal. They have to be for the same "offence" also such warnings are time limited.
I think:) but a rep can explain the system or call on more experienced colleagues. Its not much but it is something.