While the frequencies commonly used for ground vehicle remote control in the US are illegal in the UK, the current bands in use in the UK are not the only ones available. So far as Im aware 40Mhz and 459Mhz are legitimate remote control bands explicitly for ground vehicles, and 27Mhz can be used for ground and air vehicles. This does not stop you using remote control equipment not explicitly designed for ground vehicles, such as 802.11 wireless networking and modems running on cellphones. Even IR could be used, so long as it is done safely.

Failsafe should be implemented above the physical networking layer - and it is, at the moment. All the failsafes Ive seen or built are independent of the RF equipment used. There is nothing inherently safe about the 40MHz band; it is just a set of numbers.