Very immigration officer I’ve ever interacted with has been chilly, it’s not some uniquely American thing.
Pretty much every rail station I went through in Europe had extremely (to my eyes) heavily armed guards standing around. I was also asked to present my passport on several occasions. At one Italian station, it happed twice within a few minutes. I’ve been on multiple trains where some flavor of police comes on, checks people’s papers, and then grab some guy and escort him off at the next stop.