I've heard similar accounts, and anecdotally holds up, although my experience travelling for work specifically is limited. Incidentally, as a Canadian, I've been searched many more times, if not 100% of the time, coming back from the states than going in. Security theater in both directions though for sure, just looking for a slip up. Going in to the states, I once had a slightly vague answer about where I was staying because I'd planned to camp on a long road trip. They pulled me into the lineup and then asked me again, I tried explaining but they just wanted an address and hinted as such, so I just google searched a hotel in front of them and gave them that. They've got boxes to check.
> They've got boxes to check.
Yup. That's it. And the people running entry and customs at airports around the world are not necessarily the most capable and accomplished among us. I have lots of stories.
For example, entering into Mexico (Cancun), there are probably twenty passport check booths. The line for passport checks easily had 500 people in it. Every single agent left their station, with only one left to process 500 people. That remained so for about an hour. As could be expected, tempers were flaring and interactions with this one person, in some cases, where, well, less than ideal. No supervisor in sight. About an hour later five agents showed-up. It was horrible, the agents had an attitude and travelers were tired and angry. I've been going to Mexico for a decade, this was the only time I've seen something like this. Someone for whom that trip was their only exposure would likely come out of it with a very different perspective.
Here's another one. I won't name the country because this was a thing at a moment in history for them and no-longer the case for probably the last twenty years. When travelling to this particular country is was an unspoken rule that you had to put money into your passport (typically $100 per traveler) in order to gain entry without being hassled. If you did not, the consequences were in a range between having to pay serious "taxes" on your stuff to having some of your things confiscated (typically your electronics).
As I said in another comment, this isn't a black and white issue, it's shades of grade.
Mexico uses passport control almost purely as a jobs program. At the land borders only the largest cities seem to check (like Tijuana), most of them don't even glance at you. The guy at the x-ray machine has been asleep a few times.
For first world entry they just depend on the fact the 1st world country is harsher on security than them so they don't bother. Might be different if you enter from Mexico's south land border.
Trip to Mexico. Get into the hotel. We bought a few things that had the kind of packaging that is impossible to open. I said "I'll go to the front desk and ask for scissors". Without missing a beat, my daughter pulls out a full size Fiskars pair of scissors from her carry-on luggage and hands them to me. The scissors made it past LAX security theater x-ray machines, etc. Hilarious and terrifying at the same time. Mexican security caught them on the way back, so we had to donate them to Mexico's GDP.
People get worked-up about interactions at airports without fully understanding their context and realities. Just chill, don't argue, don't be an idiot and enjoy the trip.