The "prison IP range"? What's that? There are literally thousands of prisons in the US (4500. We've got more than any other country in the world, go us.)

Wikipedia certainly is not interested in the task of trying to track the IP addresses of each of these prisons.

(Also, I can guarantee you that the vast majority of these prisons are served by under-resourced barely-competent IT departments.)

(Also, it may not even be possible to distinguish between 'inmate' IP addresses, and IP addresses used by staff, or even staff working for the department of corrections not even physically at the prison. Why? Because there's no such thing as an 'inmate IP address', because right now inmates aren't allowed to use the internet at all. So you're asking under-resourced barely competent IT departments to set up a new IP address allocation regime. At 4500 different prisons.)

I'm just wondering: is the high incarceration rate in the U.S. somehow connected to it's multi-ethnic makeup?

In Europe, and other places/countries with more homogeneous ethnic makeups, the incarceration doesn't seem to be that high. Scandinavia, for example.

I think it is, in the sense that the US is a country founded on one group of people imprisoning and disposessing other groups of people for economic profit, with those groups differentiated by ethnicity. But NOT if you're suggesting that a place with a hetereogenous ethnic or cultural makeup is neccesarily more violent or something.

Also, in fact, when you say "in other places with X, the incarceration rate doesn't seem to be as high", X can be _anything_. The US has the highest incarceration rate on the planet, by a fairly wide margin. So in EVERY other place, with any characteristic at all, the incarceration rate isn't as high. Not in Scandinavia, not in China, not in any part of Africa, not in Mexico, not anywhere. The US is alone.

That wouldn't stop editing through a proxy.

You'd have to have someone white-listing that proxy. And I don't see that happening.