Not all of us have cell plans with hotspots ($$$), hotspots often have data caps, cell is often slower or congested, and there are some areas without cell signal. It's also kind of silly from a wider perspective to shove everyone onto the cellular network when most businesses have perfectly decent fiber internet nowadays.

Sure, I'm usually on hotspot, but I personally appreciate when businesses have wifi. Either way, there are always going to be shared networks somewhere.