Hi Cameo...
I agree that sometimes the course of least resistance will get you out of an investigative situation more quickly. Typically, and I can only speak for myself and fellow department members, we aren't looking to "jack" people up. I would guess that I am interested in searching less than 10% of the vehicles I stop. I will try to get into a car if I strongly suspect that there is contraband in the vehicle...especially weapons. I work in Southern California, which has a high concentration of gang members of all types, and finding guns in cars is quite a common occurrence. Drugs like meth, heroin and cocaine are often associated with crimes such as burglary, so if I find dope I also look for property in the car that might be stolen. I am not interested in finding a small amount of marijuana in a car, but rather things that pose a public safety risk. I make no apologies for using whatever legal means I can to get into the car of someone who needs to go to jail. I don't condone violating people's rights to accomplish this, but anything legal is fair game.
Typically, I suggest to people that when dealing with law enforcement to consider the "attitude test". If you are uncooperative, disrespectful or rude to an officer, it is likely you will fail the attitude test and subject yourself to that officers suspicions regarding your actions. Can some officers treat you differently for being a "jerk"...sure...but any cop with a few years on has heard it all numerous times, so the attitude will roll off their backs. When someone treats me with disrespect and demands their rights, it raises a red flag to me that there is something more than a civil rights issue here, and makes me want to look deeper. I won't violate your rights, but I will exhaust every legal avenue available to me to investigate the situation.
On the border issue, I believe this has been the case for quite a while. Here in So Cal, we have permanent border checkpoints located 40-50 miles from the actual border...if you are stopped, you can be required to prove your right to be in the U.S.