I'm non-union and involved in installing new machines in a union business. They require us to hire union people to do the installation while we are restricted to supervision. So they do indeed do that.
As for higher wages across the board? Unions these days are pretty self-serving, even amongst their own. Thus you get two-tier wage levels or even three or four tiers in some cases. The older guys won't vote in lowering their $30/hr operator wages, so they cut more from the new guys who aren't voting yet, who end up getting around $14/hr with minimal increases.
"Regardless of the legal speed limit, your Buick must be operated at speeds faster than 85 MPH (140kph)." -- 1987 Buick Grand National owners manual.