General Discussion

Workers were hired on a seasonal basis by the the pharaoh's court, local temples and skilled craftsman who brought the workers in, paid in beer, bread, and other goods, could bring their families, had hospital services and housing on the work site.

If they wanted to return home to work the family farm, business, or take care of family, they were paid what they had earned, and went home.
If they wanted to go back, they could.

Egyptians that weren't nobility, religious members, or wealthy landowners, trades or craftsfolk, were either paid servants or working class.

Slaves were criminals. Or uncivilized war prisoners.

So the Pharaoh really did not want slaves touching or doing anything that had to do with creating the memorial to His (or Her) greatness. Pharaoh wanted people who wanted to work for that greatness, not forced to.

Now, when the Greeks beat the Egyptians and took over the kingdom, they started using slave labor for public works.

But not the Egyptians.