Do they really not teach u how to backup these days ?

I dont think anyone here is saying that they (we/I) learned to back professionally in one day. The thread is a discussion (at least in my view) of how, just the reference to "truck driving school" is a falsehood... a slide of hand... a misrepresentation of what they actually do.
Just like the OP's question......

I agree with a lot of your post that its the industries fault that the system is the way it is.
Personally, I believe that a driver student should have to attend a "Truck Driving School" for 6 months (just like a police officer, a fire fighter or an EMT) that actually teaches individual students how to drive a truck, the industry rules/regulations & provide actual physical training behind the wheel, on the road, actually dealing with loads/shippers/receivers.
Then be required to stay with a trainer at a company for another 6 months.... minimum.

And there may be some truth to the guys your calling super truckers referring to they're ability at such young ages or the ability to learn these things so quickly. Or at least learning this stuff quicker than students today.
Some of us older guys (from the 50's & 60's) came from an entirely different generation & era than younger drivers today. I did all the things you say in your post. I came up from a very young age doing things that gave me a lot of early experience that younger drivers today don't have. I was on a farm tractor prior to 10 years old. I was driving a vehicle with a manual transmission by 12 years old... yes, on the road. Yes, the first time I ever sat in commercial vehicle... and old international with a 10 speed (5 speed with a dog)... I was taken to the truck & dropped off with the keys & was told; "take this truck to my ranch" & drove it about 20 miles across the parish (county).

It didn't take a lot of training for us. We came up doing things that were physical. We didn't come up sitting on the bed playing video games. We came up in a time where physics & mechanics was a part of our everyday life. We didn't have to be taught as such. It was how we were brought up. The environment.

We could reverse this & put our shoes on the other feet. I can't get the full use of electronics. I cant understand a tenth of my Xfinity TV or my old iPhone 8. But I can give either to my 10 year old grandson who has never experience Xfinity (cause they have Hulu or something) & my iPhone 8 and there's no limit to what he can do with that thing within a few minutes. Why?? because that's how he came up. He came up from a 2 year old, with electronics in his hands. Its all he does. Its what has developed him. But you know what? He cant back a 70 ft rig into a tight dock between two long nose Pete's either. Why?? Because he has no understanding of physics. He has no understanding of mechanics. He's lucky to figure out how to operate the door handle to get out of his bedroom.

Its not that I am a super trucker... we just came up in a different environment. I learned to do this stuff before I even knew, consciously, that I was even doing it. Just like my grandson with a video game. He don't even realize that he has to learn how to make Mario jump over a mote to reach the castle. Actually, he didnt have to learn it. He just knows how to do it. Its just natural to him. There is no learning with him for that.
Yes, I probably learned it quicker & easier than he can, but he can learn electronics easier than I could.

Now....... End of my rant......