Question

What's the greatest problem unions face?

Answer 1

interest based conflicts.

Answer 2

Declining membership. I think less than 5% of the private workforce is now unionized, and it continues to shrink every year. Even now, the only unions with serious state-wide or nation-wide influence are the public employee unions, e.g. the teachers' unions, the state workers' union, the prison guards' union, the police and firefighters' union, etc.