It's US law. Are there similar European laws?

The European attitude is: Am I breaking the law? How do I make sure I’m not?

The American attitude is: I’m not breaking the law until someone tells me to stop.

The European (ok, Swedish) attitude is: the authorities are there to enforce the law.

The American attitude is: the law is there to support the authorities.

Sweden until early 2000's maybe

I would say the American attitude is more like "don't ask, don't tell."

French people have the us attitude. Germans are geniuses at rule breaking without breaking the law xD

Yeah, however, the problem with breaking laws around immigration in a place you like is that you won't have to do much to become ineligible for the convenient visa options. As in, get caught by immigration working on a tourist visa, get no tourist visa approved for the next 10~20 years. If you get a visa at all, that is, though I understand merely violating conditions, not breaking normal laws or overstaying has no good reason to get you banned from entry itself.

You can be banned from the US for any reason, or no reason, just because they don’t like the look of your face, or the officer is having a bad day, etc.

Regardless of what the law says you don’t have any right to enter the US, regardless of what visa you hold (except perhaps a green card), so be friendly, look wealthy and important, and say the right things.

Haha Spain and Italy are like: rules are stupid and there to be broken

"Más vale pedir perdón que permiso"

As a European I expect at least some common sense behind a law.

Every time I visited the US I noted a complete absence of common sense.

You only get common sense when everyone agrees with what the goal of the law should be.

Laws in probably every other country are the same in this regard. If you enter the country and do any work under the wrong visa, it is an improper entry.

That's correct.

But only when entering the US I have been asked for example: Do intented to engage in illegal activity?

That's question seems to violate common sense: No one intending to do so would admit it.

Nobody expects you to say "yes, I want to defraud old people" but if evidence comes up that you intended to do illegal stuff they now have a simple case of you lying to the immigration officer.

Similarly to how you are supposed to pay taxes on income of illegal activities, if they find stacks of cash in your house it becomes easier to convict you.

They are weird laws but have their uses (good or bad)

A direct question like that is seen to be useful as part of a broader set of questions, due to the emotional effect on the interviewee, depending on the "interviewing technique" that the agency is using.

US immigration is a nightmare. Even as a German with a Green Card, it was always extremely stressful.