What efficiency? That of the manufacturer's sales team?
A series diode is only a 0.6V drop and, for low-power devices like these, its power use is comparable to all those fancy LEDs in the front. Only that none of these LEDs will protect the device from plugging the wrong supply.
ADSL modem and ethernet router, same brand. Same connector for the DC power supply. Opposite polarities. So if they were ever unplugged at the same time there was a 50% chance of letting the magic smoke out, which did happen.
A pair of devices so brokenly designed can't, of course, include a series diode. Oh no, that would cost one more cent per device - prohibitive!
Electric power steering feels like crap, though
As a 3rd gen Prius user, I beg to differ. Granted, it's not the addictive feel of a BMW coupe, but it feels just fine and if I have to find something needing improvement it's the initial response. But I am rather pleased with this car's handling and especially its power steering, all things considered.
you can have guns
You say that as if it was a great thing. What is so cool about everyone in a country with a nine-digit population (which statistically makes the percentage of insane people millions) being able to have deadly weapons with them at all times?
Personally, in that regard I feel much more secure in my country (which is in the EU, by the way) because people can carry guns if: (a) they work for the police, (b) they work for the army (and then not at all times) or (c) has been life-threatened, and a judge decides the threat is serious. All of them have to pass an exam to assess their suitability to carry guns, kind of ensures his/her sanity. Add to that another special permit for sports, which does also require an examination, and allows only for certain classes of weapons and ammunitions. Net result? No guns in the streets. Almost no deaths by gunfire. When there is a shot in the street, it hits the news because it's so rare.
"Protozoa are small, and bacteria are small, but viruses are smaller than the both put together."