The scanner licence was a trial balloon that was considered to generate revenue and potentially track scanner users. It was deemed a logistical impossibility due to the number of sources for new scanners and scanning (SDRs etc) equipment. Not to mention existing scanners. Also differentiating between open freq services (CB, Marine, Ham etc) and desired closed services (police, fire, EMS, MOE,MNR etc etc etc) for enforcement.
I even heard (rumor and not necessarily true or accurate) that even knowing the freq for certain services would be "a violation" of licence. No one could figure out how to see if 155.400 was in your head or not
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