As a purchaser, you're not bound to simply abdicate responsibility if your contractor misbehaves. You have the right and ability to choose contractors whose values are aligned with yours, and refuse to do business with those whose values don't. And you can reflect those values in the terms and conditions of the contract.

See, for example, Apple's supplier code of conduct: https://www.apple.com/supplier-responsibility/

Consider for yourself: if you hired a contractor to remodel your house, and you found out that the contractor wasn't giving their employees bathroom breaks, would you simply shrug your shoulders?