This is completely normal inside the EU. You barely notice you're in another country sometimes.
As a result I make a habit of not going to the Hostile States of Overarmed Americans despite it being only an hour away. The people are super nice, the government... not so much.
Are the Canadian agents hostile as well, or only the American ones?
>The people are super nice, the government... not so much.
The Americans that tend to go into law enforcement jobs are not super nice people, quite the opposite really. It's really eye-opening going to other countries outside the US and interacting with cops and other law enforcement agents (including airport security and customs agents) and seeing just how differently you're treated. Even as a US citizen, entering the US is not a fun experience at all.
Returning to your own country doesn't mean the agents have to be friendly to you. I'm American and the agents there are not friendly when I return. They don't just do it to non-citizens; they're assholes to everyone. Of course, there's a lot more limitations on what they can do to US citizens than to foreigners, but they don't turn into nice guys when they see a US passport.
Every time I've visited Canada, the agents there were reasonably friendly to me too. To me, this shows that the two countries simply have extremely different standards in what kind of people they hire to be agents, and how agents are allowed to act.
https://mrgris.com/travel/blog/labrador/3/
Quote from the Canadian border guard about the neighbouring US customs officials: "ah yes, they have a... different frame of mind"
Of course, if your car isn't registered in an Eastern European country you probably won't even know that this is a possibility.