Of course it's already being used. When Average Joe thinks about a criminal he thinks some thug hood with a brick.
The professional criminals are affiliated with syndicates and mafias have money and resources. They can hire the talent able to figure out decoding these trivial radio signals.
> They can hire the talent able to figure out decoding these trivial radio signals.
I don't expect even older radio access systems to be that simple to abuse. For example this application note from Atmel[0] describes such a system. It uses an AES-based MAC and a rolling window counter to prevent message spoofing and replay. I wouldn't bet this implementation is actually secure, but it's not so trivial to attack.
Please note I'm not saying that criminals haven't abused vulnerabilities in these systems, just that it's not a simple matter of 'decoding these trivial radio signals'.
The professional criminals are affiliated with syndicates and mafias have money and resources. They can hire the talent able to figure out decoding these trivial radio signals.