Why car salesmen in North America are so rude? Asian exchange student look for my 1st car?

I have never shopped for a vehicle in North America before. I have my budget and know exactly what I want. In China, most of cabs are Jetta, they were very reliable. Good enough for cabs; then good enough for me. So i use the same theory… Look for Ford Crown Victoria. As they are big and seemed to be well built. So I go to the dealership. According to the internet, I should look for idle hours. For example, most of those cabs or ex police cars do idle a lot. Ford website said 1 hour=33 miles. A few of them i looked had 1000 hours;aka 33000miles to be added. So i told the dealership. The guy said i was new to the country and do not know what I am talking about. I should look for BMW or Honda Accord. I told them I do not like those. Costs too much to maintain. Since I live in Canada now; i'd rather buy a made in Canada vehicle. But none of salesmen like what I told them. But they seemed to insist I shouldn't buy a Crown Vic; but BMW only… Why car salesmen in North America seemed to believe they know me better and never listen to me? That's just rude. This is the same in Canada and the US. I have looked for both countries for vehicles. I think I should just go to the government surplus instead to avoid them.
Added (1). why a car salesman said:"Asians should not drive a redneck vehicle?" I have to google it. It means "poor white man". What's wrong with them? Dont western culture value individualism? Just because I am asian; does not mean I like Honda ONLY. Btw? What's wrong with driving a "poor white man"'s vehicle like Ford?
Added (2). The reason I was looking for a Ford Crown Victoria; we watched a lot of American movies in China. Crown Vics seemed to be cool. Good enough for police officers; then good enough for me. I can't believe 4 out 5 dealerships I asked; insist I shouldn't buy a Ford Crown Victoria; wanna sell me something else. That's just crazy.
Added (3). Is this very funny for car dealerships that an Asian was looking for a Ford Crown Vic? I have never expected that. I mean there were Chinese back home drive Chevy and Ford pickups. A lot of them. So they are all "rednecks" according to car salesman.

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