Are you sure your union isn’t helping? No union is going to be run by miracle workers, but that doesn’t mean they don’t improve conditions. I can’t say for sure, but I suspect this sentiment is part of why union membership fell apart in the 20th century “well my union doesn’t do anything for me anyways.”
Like democracy, unions do require some upkeep via people stepping up. If you don’t like how your union is performing, you could consider becoming a rep (admittedly based on my limited understanding as a non-union employee).