This argument doesn’t hold though because a single bad actor who figures out how to spoof the interface has tremendous leverage to hurt a lot of people at once. And it’s likely they could leave a device at night and trigger it days or weeks later. One instance of this could literally cause enough public fear to get AVs banned for years.

I agree with OP that each car managing its own cameras and radar makes the most sense. Cooperation by way of individual optimization is the cornerstone of modern society and something we should absolutely imbue our autonomous vehicles with.