[0xEF]

I've been to a lot of countries (and thus through a lot of customs agents), the most they ever ask me to do, if anything at all, is turn the laptop on. I think the point is they want to make sure it's an actual laptop and not just a shell hiding something else. I've never had an agent touch my machine or show any interest in doing so, and I say that as someone who gets the extra searches often because I carry a lot of odd looking parts and small tools for work. Just pointing that out because I think the paranoia about what customs agents are allowed to do is a bit overblown unless you're suspected of smuggling or transporting something nefarious. They're not interested in what's on your laptop until you give them a reason to be.

[tauntz]

I almost got denied boarding for a EU -> US flight ~13 years ago because the TSA agent at the gate noticed my 2011 MBP had 2 screws missing on the bottom panel (I've opened it up a bunch of times and lost some screws in the process). It didn't convince them that I turned it on and logged in etc. They still had doubts because, apparently, missing screws on a macbook was unheard of.. in the end, they held up the plane for ~10 mins due to waiting for a go/no-go decision via phone from some decision maker at the airline (as the final call was apparently theirs to make for some reason). Luckily, they were OK with missing screws and I was let on board.

[bartread]

I think it probably depends where you're going. We have relatives in a country where it might be a bit more of a concern, and we did briefly research taking a trip there to visit them, which is when all of this came up. In the end, for a variety of reasons, we decided it was going to be too risky to take that trip unless and until conditions change.

There are many countries where I wouldn't be at all worried about that, but I'd still be concerned about the possibility of theft (which, let's be real, can happen anywhere: I went on a trip to Switzerland once - generally considered very safe and low crime - where somebody had their laptop stolen from their room).