How about arithmetic? Do you need to be able to add, subtract, multiply, or divide by hand? Remember how to do square roots? (gotcha!) Why learn — we have simple electronic devices to do that — and more accurately.
Back to the original question. Knowing how to run a manual shift is required only if it’s on the car that you take the driver’s test in. I know lots of folks — and most young folks that have no idea. If you asked them why there are gears in the first place, their answer will be, “gears”?
Some folks say that soon we’ll not even have to (learn to) drive. Robots will do it or us. Self driving cars exist now. Getting it to happen is not easy, but not all that difficult either. One simplifier is that it’s mostly a two-dimensional problem — you do need a “road map”.
So, in general, how much do you need to know and what skills to you need to operate a very complex device? Take your pick — computer, car, airplane, software, TV, washing machine, iPad, cell phone, etc.
The answer is (of course), “It depends”. If the devices are designed properly, then then the level of knowledge that you need just depends on how you are going to use it.
My advice (did you ask?) is to know some things at a level more basic than your current operating level — that way if something goes wrong, you might be able to do something about it (call the help line?).
If you are just driving around in your SUV (automatic transmission) then knowing about and how to use a manual transmission is of no value. You probably know about filling up the gas tank, or having the brakes checked if they feel a little “spongy”. But if someone offered to explain how to change the spark plugs — would you even listen? Who cares? A valve job? Forget it.
But if you were thinking of becoming a mechanic, you might realize that you will need to know things like that. Now, back to computers & their programming.
My first computer language was the machine language of the University of Illinois’ computer, “The Illiac” — it filled a large room — were talking 1958. Since then I’ve programmed using some 15 or 20 different languages.
Should you learn some machine language? Certainly not necessary, but understand that 100% of whatever you program has to end up as binary machine instructions used by a non-intelligent machine — and they better be correct!
Remember the old line, “A modern computer can make more mistakes in a millisecond than 1000 accountants can make in a year.”