Sure, I agree that's an interesting and likely solvable technical problem. However, the vast majority of the addressable market in today's over-secured society don't really need improved detection. Concert venues, sports arenas and similar customers buy massive volume and they are much more concerned with faster throughput enabled by shorter cycle time and minimal false positives. Of course the head of security at Madison Square Garden can never publicly admit they don't care about better detection enough to pay more for it, but I'm confident the sales managers at these security vendors understand exactly what their largest market segments really care about.

Customers like Tel Aviv International Airport, who actually care to some meaningful extent about improved detection, are a small minority segment of the overall market. Creating new technical measures able to demonstrate improved performance in rigorous objective tests on the metrics these customers care about (some sweeter spot on the matrix of false pos, false neg, true pos, true neg, net throughput, cost) would be valuable but only to that small segment.

Note that I said lower false positives and equal or slightly better false negatives, which aligns with what you say customers want.

Of course I suspect venues really don't care about false negative rates much at all, so there's a big temptation for everyone to just turn sensitivity down.

Very likely, but who's going to pay for the engineering efforts? If the customer doesn't care about having a better device, or a better device would actually make their job harder, then it's wasted effort on the part of the manufacturer.

Engineering exists to solve a problem. It's entirely likely that your definition of the "problem" differs from that of the paying customer.