I believe they fall under the "amateur" bands. I.e. frequencies not requiring a license to utilize (given you obey given power limits). That's why the same frequencies are shared by WiFi, Bluetooth, ZigBee, etc.
Some of the amateur bands also overlap with allocations for things like radar. For example, a subset of the "5Ghz" WiFi channels (the "DFS" channels) can only be used if the access point will auto switch to a different channel upon detecting a radar pulse.
Some of the amateur bands also overlap with allocations for things like radar. For example, a subset of the "5Ghz" WiFi channels (the "DFS" channels) can only be used if the access point will auto switch to a different channel upon detecting a radar pulse.