Unions certainly should work for the benefit of employees, while employer's associations certainly should cater to the interest of the industry.

Unions are a required counter-balance to the forces of business who employ people. If either end dominates, things go sour very quickly. It's the state and government that should maintain this power balance between these out so that neither party is in the position to dictate decisions to overrule the other party.

That is for the benefit of the society.