I think it ultimately comes down to the type of person working in airport security -- in Russia, you interact with police or military affiliated staff when you

I think it ultimately comes down to the type of person working in airport security -- in Russia, you interact with police or military affiliated staff when you "enjoy" special attention. In the US, you're dealing with a very numerous staff of people without special training being paraded as a type of "elite security" for the country. Anecdotally, at the US border, I've had TSA deny a small wooden children's toy because they got drunk on a fiction that I could break it or combine it with other items to make some sort of weapon (a ridiculous idea), and, on another instance, deny a carabiner because they believed I could use it as a sort of "brass knuckles" (also ridiculous and demonstrative that none of the involved parties were even passingly familiar with punching (as a carabiner would simply cut into the puncher's hand)). At the Russian border, I misheard an important question and answered incorrectly, and the treatment was professional and grounded in reality (confirmation of the type of work I do, my documents, and my purpose for being in the country). On the American side, the workers have big imaginations and are incentivized to invent things to catch. On the Russian side, they're looking for suspicious outliers.