Stakeouts and trailing cars don't require a warrant. If the police want to hang out on your street all day and follow you around, they can do that. This issue was discussed when the court was ruling on whether GPS tracking required a warrant.

So the courts WOULD be sympathetic if

The difference is that stakeouts/surveillance require proactive, labor intensive activity (you need 1 or more people to follow an identified target) and newer methods are wide nets that capture everybody preemptively.

I'm not pro-big brother, but in general what happens on public roads (and in view of public roads) is considered fair game. What is changing is the ability to capture and store that information on a large scale, and the impacts on personal privacy.

Mayor Bloomberg also announced that police would be "stop and frisk"ing individuals with a BMI over 30 to search for contraband oversized sodas.