I think anti-union sentiment comes from the practical reality which is if you go to union-towns, they often look bombed out and horrible. The UAW, arguably the largest private union in the US, was founded in Flint, Michigan. The union didn't care about the city or its future, it simply sucked money out of the economy until there was nothing left, and then they ran off to DC. Conversely, industry towns without unions are usually nice places to live as the companies continue to invest money in them to attract more employees. This is a pattern we see over and over again, and in my opinion has led to the strong anti-union sentiment we see all over the midwest rust belt.