You would be extremely surprised. Car maintenance is expensive, and lack of inspection very often leads to people driving vehicles that should have been off the road years ago simply because a lot of states that axe it, axe inspections because they're expensive for the driver (a lot of these states are in the former Steel Belt). In better-off areas or places where people have more time/money/equipment/space to wrench on cars, then yes, but here in my city, I definitely have seen cars where the entire frame is basically being held together by Bondo and prayer, cars where they're running on 4 spares, cars where enormous sections of the body paneling are just gone. I've nearly been hit by people who clearly relied on yearly inspections to tell them "hey your brakes are failing" because they drive on autopilot and just adjust how they drive to accommodate failing/failed brakes.

In fact, I suspect maintenance costs are HIGHER in areas without inspection, because shops could rely on that regular-ish influx of cash even if it was only like $50-$100 a vehicle, AND you have the customer in the shop, so it's easier to go "hey you really need brakes, it'll cost you an extra $200 and take an extra hour or two".

I worked at a car repair shop when I was younger. I agree that it's not most (as in > 50%) but the number of people who knowingly drive very unsafe vehicles is bigger than you'd think.

That is actually surprising, given people.

Survivorship bias

Eh. I've seen enough 300+ HP cars with 10+ year old bald tires and paper thin brake discs to believe otherwise. I personally know two people whose cars have broken wipers that simply don't work. They don't care. I know one guy whose car's passenger door can only be opened by sticking the designated door opening pliers, which are stored under the seat, into the door panel through the hole of that door lock indicator peg thing and then fishing for some lever or whatever. You're simply not gonna be opening that door in an emergency. One dude at my office has an old manual BMW with a shifter knob that just loosely sits on its lever, and can easily come off if you are not careful. Gotta blindly maneuver the knob back onto its spot underneath the leather cover when that happens. He drives it like that daily. No shortage of hideously dirty diesel engines. No shortage of badly misaligned headlights, nonfunctional brake lights, overly loud engines etc.

In short I not only think state inspections are a good idea, I even think they should be even stricter.