I think we need to ask why those people were willing to work on pyramid building project in the first place. (To be specific, I’m talking about the your hypothetical modern day workers, not the ancient slaves of Egypt.) Why are people willing to do work in the first place?
Isn’t the answer the same in either case? What fraction of people working jobs, and especially low-wage jobs, are doing what they really want to do with their time? Many would say wages are just another form of slavery.