They don’t take in hundreds of people per day. They might not even average one person per day. There’s no way it would be worth the $150-200K it would cost.

Unfortunately, our mental health institutions don’t receive as much funding as they deserve. One out of every five adults in the US is living with a mental illness (source). I know I would be really pissed off if someone strip-searched me and forced me to shower.

In addition to the other reply, they actually don’t catch everything. Metal detectors only catch items of sufficient size, and the only body scan that would be adequate would be a full body x-ray, which would both pose a significant radiation health risk as most medically necessary x-rays are specifically limited to only the necessary area (and especially if the patient is admitted multiple times) and which would require you to wait in a smaller and less comfortable holding area for many hours until it is fully reviewed (even a small medically necessary x-ray can take several hours to be examined). An airline (for instance) justifies the increased risk of not doing a full body x-ray by

a) the passengers having a relatively lower risk of violence, self injury, and confusion and greater ability to comprehend and avoid consequences

b) careful screening / background checks where a high risk result means they can just refuse the passenger altogether. We are only allowed to refuse patients if we are a low acuity unit or if the patient has too many medical comorbidities / co-occuring conditions.