That is what Economist Leonard Rapping called "spill over" - one non-union employer pay its workers a significant premium to bribe them not to join a union. If you happen to work for that
particular non-union employer it's not a bad deal.
I lived in the Steel Valley south east of Pittsburgh PA -- and the unions created the American middle class.
And the unions didn't kill steel or autos -- nincompoop MBA's who didn't have the brains they were born with did.
MBA schools ruin more good engineers ...