Those ‘small’ interactions maybe benign for you but where I grew up there was non 0% chance they’d take the phone and run away if I asked them to take photo. I don’t think you truly appreciate how much trust your country has.
Some families have been trained to choose not to ask someone for any reason. There is also the common experience that someone will say no or ignore your request for photo-taking in the US (as well as there being a nonzero chance they run with it). The underlying issue is it's more about trust in risk management. Who wants to get a possible $1000 ticket and probation for a 200$ phone? There are much easier ways to snag a phone (bars, resorts, pickpocketing, etc). A thief certainly isn't going to do it at somewhere like Disneyland or Mount Rushmore, where there's a zero chance that you'll get away if there's an incident. Is it really about trust in the people? Not in the way the article describes.
I don't know enough about the Eiffel Tower, since I was focusing on the US, where I have decades of experiences.
Disneyland has active cameras over every visible square inch of the part (including along the floors, dark corners, under the trash cans, et al). The Disneyland agents acting as tourists also roam the park and monitor suspicious activity. Anaheim's Disneyland is easily the most monitored public space on the planet. Pickpockets can still move about, but they don't tend to take phones from people in the open and then run with them. My comments were in the context of existing overt trust, not the gamut of every possible criminal activity. Pickpocketing, confidence schemes, violence, etc notwithstanding. The movie, "Welcome to the Giftshop", which is partly about Banksy, makes note of how Disneyland is harder to do something overt than the manned wall between Israel and Palestine.
Rushmore National Memorial is a difficult place to commit crimes in for other reasons. First, there are very few roads that come in and go out. The walkway up, that is commonly traveled, is lengthy, not very densely populated, and requires going through the giftshop. It's remote in a practical way, making it a very simple place to lockdown (just like Disneyland). Second, it's got enough federal employees to quickly act and they tend to do so with wide authority. Any sort of overt activity at the park, would be far more risky than going down the road to one of the bordering tourist trap towns 10 minutes away in multiple directions.