Earlier quoted context omitted.
Well, engine braking to the red light would have been more efficient. :) But indeed, automatic cars are less efficient. They do not know what you will do next, so they often make erroneous gear shifts that waste fuel and time. They don't know when to coast or when to engine brake (For older transmissions, the overdrive gear had permanent coasting, and could not engine brake at all), often have lossy pumps, etc. Dual…
I am from Brazil, here the population hates "hydramatic" cars as they call automatic cars. I saw one accident that the cause was lack of transmission knowing the future: road crossing, bad road signs didn't made clear who had priority, so both drivers went forward. Both cars tried then to stop, but the automatic car instead had just shifted up, then as the driver tried to stop, it lurched forward and hit the other ca…
In a manual, you can of course clutch out as long as your clutch cable (or hose for hydraulic clutched cars) doesn't fail, which is not an option you have for automatics. These kinds of failures do occur today, though. See the famous Toyota "unintentional acceleration" scandal, where a software error read "0% throttle" as "100% THROTTLE GO GO GO GO", causing death in a few cases. There's also a case of a person that was stuck in a car that could not stop, driving at constantly increasing speed on the highways of France, IIRC. He couldn't turn the car off or get it out of gear. You can disengage a manual if you're quick with an intact clutch cable, but you're a bit lost in an automatic, especially if it's too powerful to hold on the brake.
Up here, manuals are normal (with automatics slowly getting more and more popular), mostly because everyone knows just fine how to drive them, and automatics are much more expensive. I, personally, can't decide which I prefer. I'd much rather drive fully manual than a "retrofitted" automatic like the one in a Lupo 3L, and I still have to try a dual clutch transmission, for which I might end up having similar opinions. They always seem to change wrong, the changes are rough and slow, and the clutch engagement is very binary, leading to odd engage/disengage.
I like conventional automatics in cars that haul heavy loads (pushing a 4 metric tonne trailer over a curb in reverse at low speeds without the possibility of gaining some speed first make you worry a lot about your clutch in a manual), and our busses and trucks are generally fully automatic, with more gears than you would bother counting.