Well of course, but there are always edge cases. Large rock, or a football? A person, vs. a cardboard cutout of a person? An empty plastic bag, vs. heavy bag with clearly something in it? A human can instantly tell the difference between all three, but for a computer to do it you would need some extremely good image recognition(in the case of a loaded bag the problem becomes near impossible, it's hard enough to just recognize something as a bag, being able to tell if it's weighted requires spatial awareness that no one proposed how to solve yet). In the meantime out best of the best image recognition software can't tell a zebra and a sofa in a zebra print apart. So for now, while we wait for the algorithms to improve, there should always be an easy (with an emphasis on easy) way to disable automatic breaking.