Characterizing vehicles based on stickers (which easily can indicate political leanings) is absolutely problematic. It's just not considered problematic by conservatives, given police in the US are overwhelmingly conservative.

Look, I agree that's problematic conceptually, but it's absolutely not what's happening. ALPRs don't select cars on spec, like, "this car looks out of place here". Nobody has time for that. They're matching specific descriptions of cars to incidents, like, "this vehicle has been present at the site of 5 previous package thefts".

Here's another way to look at this. Municipalities are the primary operators of ALPR cameras. Any municipality that would scan bumper stickers looking for Trump opponents is not going to be receptive to any appeals for regulation.

One problem with this whole debate is that people are coming to it with movie plot concerns rather than understanding what's actually happening with them. That wouldn't be a big deal if this was a slam dunk public policy case, but it isn't: there is broad bipartisan support for these devices.

There are deeply problematic things happening just with license plate pings!