I think you are right that drivers will pay more attention to them, but I came to the opposite conclusion.

They look big enough to cause serious damage to your car if you hit one, so I think you are right that drivers will pay attention to them. But I think drivers will also want to pass them, increasing the chances that drivers will use the bike lanes as passing lanes.

Furthermore, I think drivers will not trust the delivery robots, so when they are passing they will be paying attention to the robot, increasing the chances the drivers will not notice a cyclist in the bike lane.

Put the robots in the bike lanes and then that increases driver attention will be going toward keeping the car out of the bike lane.