Yeah the vehicular ownership rate only increased from 80% or whatever in the 60s to about 90% now a days. But I'm not saying that's why the increase in vehicles probably isn't a big factor. What I'm saying is that vehicular theft is a very intentional crime. Crimes like phone theft are highly opportunistic - somebody sees a fancy phone somebody forgot, and just decides to pocket it. So more people have more phones means more crime due to more random opportunity. But car theft is overwhelmingly a targeted crime, so changes in the number of cars is going to have a pretty negligible effect above some baseline point. It's like bank robbery - you're not going to just inherently have more bank robberies per capita because there are more banks.
Here’s one scholarly analysis, but I don’t want to get into various assumptions underlying such extrapolations: https://www.jstor.org/stable/2061893?x=-53.76031957390146&y=...
Households generally hold multiple people, a spouse, teen, or grandparent without a car can’t have their car stolen.
As to car theft being targeted, chop shops can only sell parts to people repairing actual cars which promotes theft based on the number of cars. Similarly local communities don’t represent the demographics of the entire country. Poor communities in 1960 had vastly fewer cars than they do today.
Similarly on the car stuff, I do agree with you. You can't strip cars for profit unless there's a minimally large number of people using cars, but we were obviously well beyond that point by 1980! 80% of households had cars! It's not like there was a shortage of people needing/wanting parts. That's far more than enough to create all the sort of venues necessary to be able to comfortably resell parts.
> It’s not like there was a shortage of people needing/wanting parts
The problem here is you get a lot of different parts from a single stolen car. Steal 10 Honda Civics and you might be able to use almost every part from the first car, but by the 10th only those parts you have 10 buyers for are valuable.
The equilibrium is a function of the number of cars people own and the percentage of mechanics willing to use stolen parts. So even if a handful of people can steal an arbitrarily larger number of cars the limiting factor is mechanics willing to use stolen parts. Total number of mechanics scale with number of cars, but the percentage of those that are criminals can vary through time.
On the car thing, I think you made some good points. I regret dragging us down this line of argumentation which has been pretty strained, though informative! You were talking about light crime in general, and I voluntarily picked cars. That was pretty stupid. Anyhow, it's been fun meeting another impassive argumentative data whore. May our kind spread! And may we disagree again, soon!
[1] - https://en.wikipedia.org/wiki/Capital_punishment_in_the_Unit...
Murder per 100k. 1960 5.1, 2014: 4.5, 2019 5.0. Go back to 1950: 5.3, 1940: 6.3 and it hit 9.5 in 1934.
PS: Lead is one factor post 1960’s, but changing demographics is another. The post war baby boom adds a lot of kids who aren’t killing anyone as preteens/young teens but average into population statistics. The low point of births during WWII is especially important when those years line up with older teens more likely to commit crimes. Add in a good economy and it’s a perfect storm for low crime.