It's crazy because the numbers don't line up with the theory. If you look at US traffic deaths by year, they were basically flat in terms of vehicle miles traveled between 2010 and 2019 and then took a big jump from COVID which is only now starting to come back down.
Meanwhile in Europe road fatalities were also fairly flat up until 2019, and then went down significantly from COVID.
Now we have to guess why the responses to COVID had the opposite effect in each place, but it's pretty obvious that the difference was a primarily result of COVID rather than differences in vehicle safety regulations, unless the vehicle safety regulations all changed in 2020 and everyone immediately replaced the installed base of cars everywhere overnight.
2020 wasn't just the start of Covid, but also the start of BLM. The narrative I always see from the American right is that BLM caused many police forces across the US to radically reduce traffic enforcement, since:
1. traffic offenders are disproportionately black,
2. stops for minor traffic offences can sometimes spiral into violence in various ways, and some viral ones have involved absurdly bad use of force decisions by officers involved, and
3. no force wants to take the blame for another George Floyd
Per this narrative, a significant antisocial tranche of the public has responded to the effective suspension of traffic law in the way that you would expect them to, and that is why road deaths are up.
The timing lines up but that's more of a vibes argument.
The majority of traffic stops in the US are, cop parks on the side of the highway somewhere the speed limit is lower than the speed people drive there, every car on the highway is doing 70 in a 55, whoever drives past gets a ticket and the government fills their coffers but the speed everybody actually drives on that stretch of highway remains 70.
Now suppose the cops stop doing that for the stated reason. If you then drive past them at 110 instead of 70, are they still going to not pull you over? Good luck with that. Even if they're actually trying to minimize traffic stops, that one's the one that makes the cut.
So then what happens if they stop doing the usual ones? People are then going to drive 70 in a 55 because they can get away with it, but that's what they were doing to begin with. You could argue that the fatality rate would be higher at 70 than 55, but then why would that change relative to the baseline where that was what was already happening?
So the argument would have to be that idiots had the impression that they could do 110 without getting pulled over, even if that wasn't true, and then did that and managed to make contact with an overpass before driving past a cop. Which doesn't seem as plausible, because speeds like that on empty desert highways shouldn't have raised the fatality rate that much (e.g. it's not that high on the autobahn in Germany), and speeds like that in traffic where there are other cars traveling significantly slower will trigger a visceral feeling of danger in nearly all humans unless they're on drugs or have significant mental health issues, and in those cases they wouldn't have been deterred by the prospect of traffic enforcement anyway. Which is why people drive somewhat over the speed limit even when that could get them a ticket -- because it doesn't feel dangerous -- but also why they don't drive a lot faster than the other cars -- because that does. Traffic enforcement or not.
Moreover, regardless of how much of a contribution was made by that vs. COVID, the numbers still don't line up with it being vehicle safety regulations.
I would guess that what matters most is stops for driving disqualified/uninsured/unregistered, DUI, running lights, and failing to yield (especially at crosswalks), and perhaps for speeding on non-highway roads where it has more of a safety impact. As you say, in the USA as in virtually every culture, almost everyone speeds in some contexts, and especially on big, multilane, motor-vehicle-only roads; enforcement of speed limits in that context is likely one of the lowest impact things police can do, but I think it's a massive error to treat "traffic stops" as a category as equivalent to that sort of enforcement specifically.
COVID happened in the year of the discontinuity and caused major changes to commuting behavior as a result of remote work, people afraid of infection avoided mass transit, many people moved out of cities or lost their jobs, people bought cars who didn't used to drive and now there are more new/inexperienced drivers with cars (and it's easier to get a license in the US than Europe), etc.
Also, the numbers for at least the US are apparently just wrong:
1.27 fatalities per 100M VMT in 2023 (the latest year with data), 1.11 in 2010, that's a difference of 14%, not 30%. Even the peak during COVID was only 24% above 2010. The only way I can see to get 30% is to use the during-COVID number for only the total number of motor vehicle fatalities without accounting for population growth or vehicle miles traveled, which is not a great metric for making comparisons.
The 30% figure is "correct" if you look at the absolute number of deaths instead of deaths per VMT. But I basically agree with you; that clearly the wrong stat to cite if you are attributing the change to vehicle safety regulations.
Even that is still wrong because you'd have to use the high water mark during COVID and not the more recent numbers which are starting to come back down.
It's crazy because the numbers don't line up with the theory. If you look at US traffic deaths by year, they were basically flat in terms of vehicle miles traveled between 2010 and 2019 and then took a big jump from COVID which is only now starting to come back down.
Meanwhile in Europe road fatalities were also fairly flat up until 2019, and then went down significantly from COVID.
Now we have to guess why the responses to COVID had the opposite effect in each place, but it's pretty obvious that the difference was a primarily result of COVID rather than differences in vehicle safety regulations, unless the vehicle safety regulations all changed in 2020 and everyone immediately replaced the installed base of cars everywhere overnight.