True, there are reasons. But I don't think looking at this stuff a priori make much sense. Weird things happen for reasons we don't know all the time.
For example, why would these reasons hold true in the US and not in Europe, where some studies show a positive (albeit weak, due, again to poor data) link between immigration and crime in some countries (which, again, could be due to a host of factors not related to immigrants being somehow more immoral than the indigent population)?
From what I can tell, the studies are all over the map and the data just isn't very good on a lot of this stuff:
en.wikipedia.org
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://aisberg.unibg.it/bitstream/10446/288/1/WPEco01(2008)Bianchi.pdf
What makes matters worse is that there are usually two factions in each nation that seem to want the numbers to be higher or lower, and so it's hard to know who to trust, who's fudging what (or redefining terms) to get the results they want.