hmm.....
At our local heavily unionized Kroeger (they're called QFC's here) you can get three half-gallon containers of milk for $5.00, or a gallon of milk for $3.75 (and that's the non-"advantage card" price).
Our equally unionized Safeway has milk (not on sale) for $3.69 a gallon. Heck, even the gas station up on the corner (which is most definitely NOT unionized) has milk for $3.80 a gallon.
It doesn't sound like the minimum wage hike has affected them much. Or they're not using it as an excuse to gouge the people who shop there.