It's a simple case of willfully hiding important information in the last place anyone will look. Awareness of these tactics is a useful skill to have in low-trust societies, and when used as a teaching tool it will guarantee the outcome to be a low-trust society.

The world is messy and "the rules" aren't often written out for us in black and white. Teaching somebody to deal with uncertainty by way of studying the problem before jumping in without the full picture doesn't seem like it would create a "low trust society" as you claim. I would suggest it creates people who might look before they leap.

We have enough people on this planet going through life without ever once thinking about what they are about to do.

I had a teacher that did this but his whole MO was teaching us good test taking habits. You speed through the easy questions so you know how much time you had to devote to the hard ones.

As a student, i remember very vividly that any potential imprecision in the question of the exam was the source of great confusion, especially since you couldn't ask the examinator for explanation (the test was supposed to be perfect).

I'm not being pedantic here, i am really furious against teachers that makes students think about the best way to disambiguate the question instead of thinking about the subject of the exam itself.

Typically the exam had pointless questions and its only purpose was to teach this particular lesson. I've never seen nor heard of a teacher using this on a test that actually mattered.