I am afraid you are right.

have them lay them 1/3 overlap instead of 1/2, it will look better. also sort through the tiles and reject the ones that are very bowed.

Ninigret I don't understand what 1/3 overlap means ? the tiles are not bowed they were just not floated even. I think

Sorry. There is no saving this. 100% redo with a different contractor. Your current one thought this looked acceptable. That says it all.

I would not accept this tile installation. But I'm also aware that The Tile Council of North America (TCNA) lists the allowable lippage at 1/16-inch or 1/32 inch plus the tile warpage, depending on the tile selected.

Large format tiles often have some degree of bowing. I believe that industry standard is to lay these tiles with one third overlap so that the highest point of the tile isn't meeting the lowest point of the tile next to it, as would be the case with 50/50 overlap. That's my understanding, anyway. So, I'd question the skills of tilers who don't know about proper overlaps for big tiles.