> if there exists any more surplus value with which they could be paid more, it is reasonable for the employer to do so and unreasonable for them not to.

The one problem in practice with this is that typically, in a retail setting, employers are in a race to the bottom, and those that don't squeeze their workers get beaten in the market by those that do. It's really the evil customers capturing everything.

Of course, in the technology industry it's par for the course -- it's basically how the patent system and certain aspects of immigration law are designed.