Efficiency is usually a tradeoff that limits flexibility. If you don't happen to need flexibility, you can have amazing efficiency: a wheel of a rail car is so much more efficient than a foot. But only when it stays on a rail.
If we look at a somehow more difficult terrain, a foot suddenly happens to be a better deal, because it adapts to a variety of conditions. Of course, at the expense of efficiency (complexity, energy consumption, need for a much more advanced control circuits, etc).
In business you usually have to have some safety margin for the unexpected. If you squeeze it out in the name of efficiency (and profit), all goes well until it does not, and then it fails much harder, maybe catastrophically.
(Nassim Taleb wrote a whole book about that, "Antifragility", where he gives a ton of fun real life examples to make basically the above point.)