As an example: Some EU government could force people to turn on side-loading to install an app that's needed if you want to access public services. The app could bypass your phone's privacy protections, and feed the data back to the local government.

In the US, if Android side-loading were more common, we'd already have this, except that companies would require it.

In the EU, they'd probably crack down on companies that tried to do this. However, although it's technically illegal for governments to do such things, apparently most governments routinely break the anti-mass-surveillance laws.

On iOS, Apple has banned many bad actors for such shenanigans (although they still allow spyware from large companies like meta and google).