Good grief Grandma70s, don't be so sensitive!!!! It's up to your sons and GC whether they want to show you their reports or not, and really - so what? You know from your son how GS is doing, do you really need to see it in writing?
I've seen some of my GC's reports, and I get general feedback from DD about how they are doing, that's good enough for me.
Just because you and your parents did things a certain way, doesn't make it LAW! Just get over it, and enjoy talking about other things with your GC, and if they choose to share stuff about school then great, if not, that is their right.