Sigh. The value you're talking about here is the cost of their labour. This is like a business owner saying that employees should value their jobs differently to their salary.
You're right in the sense that capitalism is fundamentally "people make agreements and decisions within what's available to them" but what's the actual issue you want capitalism to solve, that doesn't create one of the massive downsides that any of capitalism's former rivals has?
E.g. monarchy can reward loyalty, but then so can capitalism. Monarchy can just also tell you to go die on a field if you don't kill the other king's people.