It's all about frequencies. Datalinks used in US UAVs may *cough* in some cases use a 5 GHz frequency band, which is also used for domestic wifi.
Unlike wifi, these datalinks are optimized for range instead of transfer rate.
Most wireless data transmission providers, at least in Europe, have begun shifting everything over to 60 GHz links due to the radio clutter stemming from domestic wifi in urban areas; 2.4 GHz links in particular have virtually disappeared, since you pretty much can't transmit anything without running into a giant cloud of emitters in that band over any city.
60 GHz is a long-time military comms frequency in the US. Wifi standard 802.11ad will also use 60 GHz, but - due to layout for very high transfer rates - likely only in a highly localized fashion which won't interfer with communications above cities.
(sorry, had to listen to a presentation on this topic this week)