I'm always thinking: actuators are close to their peak efficiency for some time now, i.e. electric motors can barely get any better. Same with with mechanical construction, materials and all the newtonian bits. These things are probably close to a theoretical optimum. Now these things weigh a certain amount for a set amount of power needed. It's all a bit like the rocket equation: the more power you need, the heavier the power supply, the bigger and heavier the motors have to be, and so on. So there's a hard limit of what an autonomous robot can do for how long. Now, the Boston Dynamics machines certainly are impressive in their promotional videos. But I've not found any reliable public information on how long their humanoid robots can operate autonomously without recharging. Minutes? Hours? Not that charging is that big of an issue, especially in a factory. But still, I'd be interested how long the machine can actually operate on its own. Maybe someone has information on that?