The limitations of things like self checkout have been largely customer driven, the expense of equipment (installation, repairs, etc...), and the logistics of such a transformation. I think there are many more hard limits on the ability to replace on site service workers with technology than most people realize. The barriers are far greater than a few dollars an hour per employee. If they weren't the low wage service workers would have already been replaced. This is also not an area that drives technological innovation, but rather benefits from advances made by other industries, so I do not believe that raising the minimum wage would escalate this process.