Depends what you mean by "scanner". I think the OP was referring to receivers that could rapidly scan a multitude of channels, then stop if one became busy. T

Depends what you mean by "scanner". I think the OP was referring to receivers that could rapidly scan a multitude of channels, then stop if one became busy. They did exist early on, but weren't really practical till synthesized (and programmable) oscillators arrived. Some military receives had mechanical push-button tuning, but programming new channels was cumbersome and slow. Of course you could just use a bank of receivers, but you need an operator at each RX, else you'll miss most of the traffic. Especially if more than one channel becomes busy. Bottom line, having access to scanners doesn't fix the problem.