I'm an American and I was annoyed at how aggressive and militarized the southern border is.
I was on a big road trip across the country visiting national parks. I went to Organ Pipe Nat. Monument in Arizona which literally touches the Mexican border.
On my way there I drove through a border patrol checkpoint 10 miles north of the border inside the US. They don't check southbound traffic, only northbound. I never entered Mexico. On the way back I had to stop at that border patrol checkpoint. The border patrol agent was basically yelling at me for my passport. I told him I didn't have it with me. He yelled to see my driver's license. I gave it to him and he yelled at me "Why do you have a North Carolina driver's license?" I replied that is where I live and that is my home address on the license. He then screamed at me "Don't you know this is a prime drug running area?!" I told him "I have no idea and I'm not interested in drugs. There is a national park area 5 miles away, don't you get a lot of tourists here going to see that?"
I then noticed in my rear view and side mirrors that another agent was going around my car with a dog sniffing around. After about 2 minutes I saw the dog agent give a thumbs up and the rude agent said "Okay, you can go but you should carry your passport"
I had less rude experiences in Texas and California but still overly suspicious border patrol agents. One guy asked me what all the stuff was in my car. I actually offered him granola bars and soda cans and then showed him landscape pictures on my cameras. He realized that I was really a tourist and not into drugs or helping immigrants cross.