I, too, was able to make A’s without studying, but I didn’t do that until I got to college. I didn’t do it prior to college because I was not motivated. It all seemed kind of silly to me as a youngster to fret over grades. My mother died when I was 11 and I fought with my dad.
This was not an environment conducive to doing well or being motivated to do well. So it would have been quite accurate to say of me that I got “bad grades because [I wasn’t] working hard enough.”
However, in college, I was married and very motivated, so I applied my innate abilities appropriately and had a 3.3 GPA (4.0 max).
Neither one of us can extrapolate our experience to come to any legitimate conclusion about education or learning abilities. Like you said, everyone is different and one cannot generalize about education based upon our personal experience with it.