This is how laws get really complicated. Wouldn't a more complex solution end up costing more (to the companies you are trying to help) than a simple solution?

It depends on what you're trying to do. Outwardly H1-Bs are supposed to be about bringing in talent that can't be filled with a US worker which should fetch a premium. To that end having just a blanket floor doesn't really make sense because a premium wage in Small Town, USA is a rounding error to large corporations in Big Tech Hub, USA. But you can't make the sliding scale too location sensitive because then you just open a new way to game the system with having big contractor sweat boxes all operating out of the middle of North Dakota or somewhere with market so tiny prices. I don't think a simple law could ever really run H1-B if the goal is 'bring in premium talent' for hard to fill positions especially in tech positions where location is becoming less and less critical.