Also what about weather patterns...
I hold an amateur radio licence and am well aware of various implications these transmissions could cause, not just for local people but even for people on the other side of the globe.
Wi-Fi and Bluetooth isn't too bad as the devices that use them barely pump out enough power or have a large enough antenna to make that kind of difference, and also use not very good frequencies, although radio is a very strange medium and even when you think everything is perfect something strange and unexpected can happen.
Radio can easily escape out of it's boundaries depending on atmospheric conditions such as weather and cause problems not just in and around the area the transmission is designed to be in, but also for many miles outside the area, and even on the other side of the world if it happens to bounce on the ionosphere.
Some examples of strange radio anomalies I've encountered which show the problem are -
When I lived in Preston I used to be able to receive Wire FM from Warrington, they're signal was so strong it used to wipe out Tower FM which was nearer to me in Bolton, and Wire FM was only supposed to have an area of Warrington, Widnes and Runcorn. My only thought on that one is that it could have been using one of the Tower FM repeaters to re-broadcast itself.
In Manchester Key 103 and Galaxy 102 (Capital 102) regularly interfere with each other, despite Key 103 being on 103Mhz and Galaxy being 1Mhz lower than Key 103, you actually can't listen to either one in Manchester as you get 5 seconds of one and then 5 seconds of another, and back to 5 seconds of one. This is caused due to the way the bandwidth of FM works, Key 103 probably have a bandwidth of over 500Khz and the same for Capital and so the two are crossing each others bandwidth and causing major interference.
In some parts of North Wales, especially Anglesey, but even on the coast near Rhyl and Towyn you can receive RTE 2FM crystal clear, and in some places on the A55 it even blocks out other local stations.
So you have to be very careful of all these problems radio can cause, even on frequencies where it sounds to your equipment that there is nothing, sometimes there can be something else there that you can't hear that someone else is trying to receive in a different location to you and you could block it out.
In addition to this you also have harmonics to think about, something that might be transmitting on the third harmonic of the frequency you are using could have it's communication interfered with, even though it sounds like the frequency you are using is empty, this includes some things like emergency services. Most people don't seem to realise that if you send something out on say for example 90Mhz you also create major interference on 270Mhz which even though you might think well that's not a problem that is outside my radio's scope as my radio only goes from 88Mhz to 108Mhz, that frequency may be being used by someone else (for example an emergency frequency) and they don't want your broadcast wandering all over it. This used to happen in Warrington a lot when a local bus company used to have their PMR for the buses on a harmonic of 97.4 so anyone listening to Rock FM used to regularly get interrupted by some bus driver reporting back to base, thankfully now they have a digital radio system so it's not as problematic, but to them they were just transmitting on what appeared to be an unused PMR frequency without realising the problems they were causing further on up the dial.