There are issues with wifi, like what if you are not on the same wifi? What if you are not on wifi at all? Also wifi does not have the same peer discovery mechanisms as bluetooth
Discussion
It's the wifi chip rather than wifi in the way you are thinking of it.
At the hackspace foundation, some members made interesting experiments with LoRa. PS I am thinking about Ofcom regulations https://static.ofcom.org.uk/static/spectrum/fat.html