See, what the problem is, is the places that decided to start raising it a few years ago to get to 15, did so at a rate of 1 dollar or even 50 cents per year, so everyone just raised their prices at the same rate.
Minimum wage increases won't work because wages aren't the problem, cost of living is. What we need to do is make laws capping (mostly rent prices) how much profit can be made on something relative to its value.
I'm not saying this is possible, or even an absolute solution, but it's the appropriate direction to solve this particular problem by and definitely better in comparison to what's happening right now.