In India, you have to pass through a metal detector to ride the metro. It seems like in US, we are trending towards needing to do the same thing.
Fear can be driven by only a few extreme examples that get a lot of coverage, meanwhile a lot of the time it would be much more likely to be concerned for the likelihood you'll get into a terrible car accident.
I'd doubtful that there's some sufficient level of policing that would make fearful people change their mind, because they're not jsut overcoming what they perceive to be extreme risk, but also overcome what they perceive to be very comfortable travel. Much like how to lose weight, you can't just go and do a bicep curl once in a while, you have to totally change your diet and habits for the long-term.
Panhandling, for example, can make people feel unsafe. You can never be sure how a person will react if you say no. It's illegal to panhandle on the subway, but still happens all the time.
I never had these fears, the car I already had was just the easier option, until it broke down. If someone were to consult me about my transit experience (albeit in a very different place) I'd tell them "Ya, sometimes there are panhandlers, sometimes there are super drunk people, but tbh I can't remember any specific examples because they're just random background noise from time to time". Meanwhile there are plenty of times I've almost been killed by cars in relatively mundane situations that I can remember specific examples of, including those I almost caused while driving and making a trivial mistake.
Should people be more concerned about hypothetical discomfort resulting from someone asking for money, or the very predictable consumption of time, energy, money, and every day life altering risk of one wrong move by anyone around them?
The latter doesn't mean I never drive, but for the 2-3 weeks a year I might need one, I just rent it, and then I'm reminded of why I don't want one, but it's nice sometimes.
(My only experience with a "metal detector" on a metro system is Bangkok's metro. The detector was unplugged at the first station, and everybody was waved past it at the second station.)
I'm all for a safer subway but your tone seems to imply that this is some out of control thing whereas it's extremely unlikely, statistically, that you will have any problem whatsoever on the subway.