I definitely haven't been shouted at in any of the European airports I've been in (from memory, KEF, HEL, AMS, MAD, BCN, NCE, and BER, so not super representative of the continent), so to me, it seems like an American phenomenon. I haven't been to Canada enough to know what it's like there. It's also somewhat recent. I've been flying for 25ish years now, and I feel like the yelling has only been happening for the past, I dunno, 5-7 years?

As others have said, I don't think it's that we like being shouted at. We just have a large number of people who are, uh, "ruggedly individual," to put it in nice terms. Those people don't really think about others enough, so you have to yell at them to get them to pay attention to the world around them. I'm the type of person that looks up the rules before I leave and makes sure I have all of my shit out of my pockets before I even enter the security line to ensure I don't reduce the efficiency of the security checkpoint. I often feel a bit exasperated with the people who don't think about others in those situations.

As a means of dealing with it, I've found that smiling, making eye contact, and nodding at the TSA agent doing the yelling makes them less likely to yell at me while simultaneously making me feel a bit less frustrated—expressing nice feelings and trying to show some common humanity with the people I'm interacting with makes it harder for me to feel angry. Not saying that'd work for everyone, but it's helpful for me.