You could just about make a speculative case for IF and flyback transmission in the old analogue days, although triangulation would have been a serious problem.
Today's digital systems are much quieter.
But the best argument is that even if they worked it wouldn't make a difference. A large team of inspectors has a list of properties without a license and they're checked in person. A complex detector van does nothing to make this easier - as proven by the complete lack of detector evidence in court cases.
You could just about make a speculative case for IF and flyback transmission in the old analogue days, although triangulation would have been a serious problem.
Today's digital systems are much quieter.
But the best argument is that even if they worked it wouldn't make a difference. A large team of inspectors has a list of properties without a license and they're checked in person. A complex detector van does nothing to make this easier - as proven by the complete lack of detector evidence in court cases.