My opinion quite heavily rests around abuse of power since i am overly suspicious of everything around me. I see getting pulled over for no reason as a wrong reason for doing so. If i am doing nothing wrong, then i feel really disturbed if cops find me interesting when they possess no probable cause. There is a such thing as getting ****ed over for no reason at all. I really don't just roll over and accept cops bothering me for no reason as a happy positive part of life thank you. You either have probable cause or not, and it's still not probable cause if you make up a reason on the spot after having pulled someone over. Don't bother people unless you have a probable cause.
The problem is, some things just can't get checked without stopping a car and inspecting it (and the driver). If you don't do that at random, then it might be too late by the time you've got a probable cause. Two examples: alcohol levels and roadworthiness.
A drunk that isn't in a completely hopeless state can usually drive straight. However, what he can't do is react to a rapidly changing situation on the road, or make snap decisions (which, as any driver can attest, are the thing separating a close call from a deadly crash). Also, this same impairment also makes them, in many cases, incapable of judging their own level of drunkness (and thus avoiding getting into cars). In most cases, you literally don't know someone is drunk until they make a mistake, which can (and often does) have lethal results. Now, you might not see that as a big issue, but in Poland (and in Russia as well), this alone is enough to justify random checks. It's not perfect (drunk drivers still drive and kill people, it's a very common comment in accident reports), but it works, both by catching them and presenting enough of a chance of getting caught to make people reconsider getting into a car after drinking alcohol (Poland has no tolerance here, anything above 0 gets you in trouble, so it
should be easy enough of a decision). Related to this is driving without a license, which seem to primarily happen because someone lost theirs for drunk driving (yes, some of them do drive drunk
and without license. Local news don't even report those unless they hurt someone, are famous or did something really dumb when stopped).
The second issue is that of cars driving when they really shouldn't. Police also check the car's papers, including the date of the last technical checkup. If you're way past the expiration date, you and your jalopy get hauled off. Poland isn't lousy with post-Soviet junk anymore, but the used car market (including imported used cars) is enormous. Add to it a peculiar tax policy that makes LPG much cheaper than gasoline, and you've got a country full of foreign jalopies running on a fuel they were never designed for. Not only that, they usually don't look the part, the differences are under the hood. If you have it regularly serviced, it sort of works, though you're better off having a backup car handy. If you don't, you never know when something will break, only that it will. If the checkup rule was not enforced like it is, some people would try to be "smart" and save money on them (since the procedure is somewhat costly). Inevitably, this would mean them driving an unroadworthy car, thus being a danger to everyone near it (themselves included). I'm not saying some people don't bribe the mechanic (they do), or that the jalopy won't completely go from "all clear" to "scrap it!" in between them, but for most, it does ensure that an expert is periodically inspecting the car.
There is certainly nothing morally reprehensible about random checks. Those things I mentioned apply to the US (or even a civilized country west of our border) in a much lesser degree, but somehow, I do get a general feeling that US roads are much less safe than European ones. As far as I'm concerned, it's a minor annoyance when it happens to you, but it doesn't happen that often and if everything's in order, they let you go with no hassle. The whole thing doesn't take longer than a drive thru run and is one of the few times our police
doesn't try to screw you over. Pull over, blow on the gizmo, show papers, on your way. A small price to pay for a definite reduction in likelihood of being crashed into by a drunk.
Also, no random customs inspections (a separate thing from police, they check your cargo for alcohol content, not your breath.

Though if you really smelled of vodka, they'd probably find a way to arrange you a meeting with police) would turn the entire Shengen area into even more of a smuggler's paradise than it already is. I don't suppose they're any serious hindrance to skilled smugglers, but they can't be completely worthless, either.