Comment by TrackerFF

I'm not a lawyer, but my work domain revolves around data analysis of certain types of crime. Often times the suspects are flagged and under surveillance, so if and when they cross borders or go through check-points where you have a great deal of authority, they'll get searched.

In many countries certain agencies / agents can do searches which normal law enforcement officers can't. Like not needing a search warrant or even probable cause. Not to mention that wiping a device could in itself be a crime, if it is suspected that evidence is being destroyed.

The key point here is that, as I wrote, some agencies have a lot of authority, and have the power to do pretty drastic stuff.