the people I work just very strongly believe union are bad. The union fees cost to much, strikes only hurt other people, we con't unionize because people need us to do our job, you can't unionize unskilled labor, My husband/wife works for and they hate it, What do they do for us nothing.
I don't know how to change people minds all I know is show them facts and they don't believe them.
What op should do it take a country like yours and put it on the same graph. If average wage goes down for your country too then it's highly likely not to be a union factor and instead something else.