You'll probably find that most price-sensitive consumer devices that don't need to interface to a standard protocol like WiFi will use very basic RF communication with a homebrew protocol. It makes the engineering cost much higher than using more complex devices, but spread over hundreds of thousands or millions of units, that cost vanishes.
OTOH, industrial markets are a lot less price sensitive. Also, quantities sold will be much less, so the device's unit price has to be higher to make building it worthwhile.
