How is this different from nuclear weapons?
Whereas a general with a drone swarm and a few thousand supporters might be able to suppress a city. Fortunately a little far fetched, but what was impossible with nukes is only impractical with drones.
Also, nuclear weapons can't be used 'a little bit' but killer robots can be -- it is much less clear where we draw the line. It seems likely that their use will be normalized/entrenched before we figure that out.
Though I hope that you're right.
I think one of the reasons why the west wants to block mainland China from manufacturing chips is to prevent them from building a robot army.
Maybe cheap LIDAR will be something we can keep a lid on? But regular vision is still likely pretty good for lining up a shot or finding a face.
Just ban general purpose computers that allow running arbitrary unsigned code. I'm sure lots of governments and corporations would be happy to get on board that one, and many end-users wouldn't notice.
Of course you could make your population turn over their old smartphones, remove IR filtering from the camera lenses and solder them to a robot body. But this will slow down manufacturing as it isn't well suited to mass manufacturing processes. Furthermore, it's a limited resource so you might have to deal with attempts by your enemy to exhaust it. Last, you'd be limited in fanciness, as in your robots can only process limited amounts. The best place to source the computation needed for really "smart" robot soldiers would probably be self driving cars as they have the AI processing power needed.