Supposedly there have been 10 "plots" in the last 12 years that have been disrupted by US government surveillance of its citizens. That's much higher than 95% yielding nothing. This is a fact, something we already know.

I think you're making a category with respect to traffic stops, though. It's not "law enforcement" at the point the searches are being done in the context of surveillance, and I'd argue that meatspace comparisons here are inapt on the whole. The level of inquiry through surveillance would be comparable to a LEO having reasonable suspicion of something, then downloading your GPS history and searching your car after you leave it at your destination (imperfect, but close enough for internet debate).