Wow. I am in a very similar situation to you - perfect match on the first three paragraphs - yet I have never experienced any of the issues you mention, period. And I fail to see any connection at all between the problems you are having and the wages you are paying, or the minimum wage.

There are certainly losers out there, and it can be hard to find quality employees, but again, what does any of this have to do with the minimum wage? Better approach: hire only great employees, pay them a lot more than minimum wage, and expect  a lot out of them.