Why are some border officers so chill and some are really harsh?

Context: I frequently drive between the US and Canada, but I’m not a citizen of either country. I have been studying in these two countries since age 13 on visas and study permits.

I have tried different border crossings, and different times to enter either country, rush hour or not. So far, I haven’t ever been denied entry, but there’s always a wide range between how much border officers try to screen for illegal activity with me.

The thing I do is always the same when crossing the border: visible side windows full down, interior lights all on, hand over neatly folder’d documents, turn off engine, and say “Hi, how’s it going?”

It’s very, very obvious when I get profiled, whether because I’m a military age male, or because of some seemingly simple reason such as bringing three vapes across the border. The questions these officers ask me reflect the reason they’re suspicious of me.

I have been searched for seemingly no reason at all, which is legal AFAIK since people don’t really have rights when crossing either border, but I am often the only person searched out of a long, long line.

I have had my every word scrutinized for many minutes, when the car in front of me spent less than 15 seconds at the checkpoint. Crossing the border as a non-citizen is stressful enough, and yet it seems that I’m expected to answer everything instantly and completely accurately. Any hesitation just results in more pressure, and I even had an officer try to go through all the steps of the Reid technique with me at the checkpoint.

Meanwhile, there’s the officer who found my place of birth interesting, and engaged in a longer but relaxed conversation about how it’s not common to see people with my passport to be born somewhere else.

There’s also the officer who very courteously reminded me to declare everything accurately, with receipts, instead of lecturing me and bending my words against myself.

I am really tired of being treated like a criminal almost half the time I want to visit family, or simply e.g. buy some bicycle parts not available in the departure country.

I need your perspective and I hope to establish some mutual understanding. I understand that border officers’ jobs are literally to protect their country from criminals and contraband, but I can’t help but think “why me?”

Is it a philosophy thing? Work ethic? Time spent on the job? Experiences on the job?

Or am I just THAT ugly?