> I was worried that they could use any crime in a broad area and just force everyone to say with who they were and what they were doing
In authoritarian countries, that absolutely happens. In America and the West, police are generally expected to have reasonable suspicion of anyone they detain to interrogate, and the length of detention is also limited if no evidence validating suspicion is forthcoming. They could not simply arrest everyone in the proximity of a crime, and geofence warrants are controversial exactly because that was the standard in the analog world.
> I was also worried than on investigations with no real crime involved, they could just go play jeopardy and ask you what you were doing minute by minute, and get you to talk until something gets inaccurate
Again, they must have reasonable suspicion to even detain you. You are reasoning about law codes as if they were literalist computer code for a compiler. The law, at least common law in America, is written by and for humans who are expected to exercise good faith as a part of enforcing and interpreting the law.
Do know your right to remain silent, and ask for a translator and consular assistance if detained or arrested. Police departments will provide these things because attorneys in court will question the reliability and admissibility of any testimony in the absence of their provision.
Don't worry too much about police if you're in America to visit. They're ordinary people who mostly want to catch criminals who are hurting their community. Bad apples are rare, and bad apples who harass someone on a tourist visa are rarer still.
