The argument for this being on topic is that
Government actions and policies obviously can impact crime rates in many ways both good and bad.
The same line of reasoning is alas true for almost anything. So valid questions for polics SE??
- What has caused climate change?
- What has caused [the] Covid-19 [pandemic]?
- What caused World War I?
- What caused the Great Depression?
- Why did people go to the moon?
- Why do some places make you poor? (Yeah, I'm not kidding.)
- Why is theft from supermakets more prevalent among rich people in a certain country?
- Why has immigration gone up or down (in some country, in some period)?
- Why is there less/more hunting done (in some country, in some period)?
- Why has air (or water) pollution gone up or down (in some country, in some period)?
- Why have abortions gone up or down (in some country, in some period)?
- Why is there a surge of infections (of some kind, in some area)?
Etc. Where do you draw the line in asking broad "why" questions where politics may have been a factor?