Well, which is it then? You hung your hat on probable cause and made a pretty big stink out of it. I think its importance has been completely overblown here, and not by me. The probable cause requirement hasn't made the police in the U.S. beloved by all or eliminated any civil rights concerns at all. The lack of a probable cause requirement up here hasn't turned us into a police state or caused rioting about police stops, or a glut in the courts about search and seizure.
And, it's not about some cops doing as they please. You'd be surprised how similar law enforcement policies and practices are from country to country, despite a few little differences in legal frameworks here and there. As I've already stated, up here, the vast majority of traffic stops are for cause. Except in rare cases of really late nights and dead traffic, you're not going to be seeing people pulled over "just because." And, if when those circumstances happen, they can't go beyond checking license and registration unless something is in plain site or occupants volunteer something.
You've been exaggerating the value of probable cause, at least all on its own. Even without a requirement for probable cause, you already have other constitutional provisions that would prohibit policing (including traffic stops) based upon race, gender, and so forth. If there is a problem with profiling based upon these criteria, then the problem is bigger than probable cause. And, if there's no problem, then it's solved by more than just a probable cause requirement, since plenty of free countries do not have that explicit requirement. There's no probable cause requirement in Canada. You still can't pull over someone because of his race. In fact, if it isn't for an investigation, an observed offence, or to check license and registration (or, as you already indicated, a big checkstop where everyone is checked), the stop is illegal.
If you want to point out something that actually creates significant differences between the two countries, offer up the Second Amendment, at least. Or, if you want to bring up something that differentiates a free legal system from others, use the presumption of innocence or the right to know one's charges.
I'd be less interested in simply "winning" our debates if you stayed in one position from which I could learn something. I think I still have several legitimate questions about American law enforcement outstanding in this thread that still haven't been answered. For instance, I'm still waiting for some clarification on impaired driving enforcement in the States. Not all of my questions are rhetorical, after all.