People with barely expired plates are normies who made a mistake. Safe. People with temps expired a year ago aren't making a mistake, they're willfully and openly displaying defiance of the law. That makes them scarier.
A car is a necessity in most of Missouri. Kansas City has more highway miles per capita than any other major city in the country (and maybe in the world); IIRC St. Louis is fourth-most highway miles per capita. Public transit has major gaps. Inability to drive is such an encumbrance that those convicted of DUI are allowed to petition courts for a hardship license allowing them to drive to work and other essential places because not allowing for this could fail under the Eighth Amendment.
All of this is to say that if you are able to pay for a car, but not the sales tax for the car, and you get pulled over for not registering after your temp tags expire, you are essentially under house arrest until you can put together the money to both pay the fine and to pay the tax on the car, which is now exponentially harder since you can't drive anywhere. Since that'd put disadvantaged people at an even greater disadvantage, it might be a "community relations" move by the PD to look the other way on these cases, at least until another blatant violation occurs.
Do you, reader, want to have to confront a bunch of scary people for a $? Oh, you think having a gun makes it a bit less scary?
Almost no one wants to confront dangerous people day in and day out. Once in a while to flex the hero complex, maybe. But a few times of that will cure you of any particular desire to seek it out.
The people that want to do that are one in a thousand types. Basically criminals themselves, just on the right side of the law who use the 'criminal' mentality for good. Most police are not that.
They want to do a job, collect a paycheck, and do it in an easy way. Like how I like to drive to work rather than do a handstand and walk 5 miles on my hands and wrists. They get little to nothing for making their job harder.
The people with the most motivation to stop the criminal is the victim themselves. You are pretty much on your own. The state won't be coming to save you.
I'm sure there are exceptions, but I think most folks (including criminals) believe crime is, generally speaking, bad. Folks commit crimes to survive, to enrich themselves, out of retribution, out of lapse of judgment, or lack of self control. Almost all some flavor of unmet needs. You put money into tackling those challenges, address why people are stealing, why turf wars break out, why addiction ruins lives and puts people in terrible positions, why poor nutrition and family support and mental health care lead to so many folks slipping through the cracks.
In other words, the main problems with schools have little to do with schools. But they’re complicated and expensive problems with distant payoff, so we keep monkeying around with schools instead.