[varjag]

The energetics of the robots are constrained by size, weight and power requirements of the components on the market. As such sure, mechanical walkers will always be much less energy efficient than wheeled vehicles of the same era. Their competition on the rough terrain however is not Segway but flying drones, which are much less energy efficient than walkers still.

There isn't any particular inefficiency in their walker balancing implementation.

[clairity]

but that's just it. the design presupposes an industrial mindset of motors and gears and pistons and rigid metal structures. it presupposes active control and computational power. it presupposes an unlimited energy supply, as would be found in a manufacturing plant.

but if we just look around, we find a huge array of locomoting, self-contained, relatively energy efficient beings to draw inspiration from.

for example, the tendons and muscles in your leg can return as much as 40% of the energy expended in locomoting. and your legs include passive mechanisms (like how your knee joint locks and the alignment of the cruciate ligaments inside it) to keep you mostly upright without a lot of active control.

nature has ingenious solutions to learn from and take advantage of.