Growing up, paper cups were all coated in wax, but I can't remember the last time I'd seen one coated in wax in the US, it's been at least a decade. Back then I remember being cautioned against using paper cups for hot drinks as it would melt the parafin (which wasn't great to drink) and then the paper would get soggy. Hot drinks to go were mostly served in styrofoam back then, while they are mostly plastic coated paper now. So that was probably a small step forward, although reusable ceramic or metal is better than either.