Forget the stupid AVs. They need streets, follow traffic rules, can relatively easy be searched, might even get stuck in a traffic jam at prime time.
A drone with GPS guidance and environment awareness can fly sufficiently close to buildings, too close for flight radar, does not need any street, cannot be searched, only taken down. If equipped with poison or explosives, the drone might not hit the target, and yet will be anything but pleasant.
The only downside is the payload. You can't load her up to kilotons TNT, though, on the other hand, the potential precision is much better, and the payload can be deposited - in average - much closer to the target.