For one, machines haven't (yet) proven as capable as them in dynamic situations. The tech both hardware and software simply isn't there yet. The fact that these Boston Dynamics robots are both loud, and have a relatively short battery life cements this current fact. This problem will likely be overcome in the next 5-10 years or less. That kind of makes it a nonstarter in and of itself. As it stands today, it is the same reason you don't (yet) have machines replacing fast food workers. The economics for most places or the actual tech simply isn't there 100%. Not yet at least.