@siri
I was merely using WiFi and Z-Wave as examples, these are not the problems with the Rachio 3 product.
Z-Wave uses 908.42MHz in the US, 868.42MHz in Europe and 921.42MHz in Australia.
The Rachio 3 uses the 902-928MHz band and hence conflicts with Australian frequencies for Z-Wave and some mobile networks.
Apparently the Rachio 2 does not have the same transmitter and would be ok in Australia.
I have not seen any Z-Wave product allow changing the frequency, they are sold in different versions for different countries. Some WiFi base-stations do support changing the frequencies (and signal strength) within limits, for example the Apple AirPort Extreme but even that did not support changing between US and Europe only within Europe - e.g. between UK and French frequencies.
See - Ability to disable Wireless Flow Meter radio? Australian usage