I watched my grandsons today, U7, young teenage female referee getting the simple ones right but getting most of the closer stuff wrong. At that level it hardly matters but I fear that when they move up they haven’t learned much and continue to not understand challenges / deflections and call incorrect throw ins the harder stuff won’t come easy either or it will end in tears by the ref or the teams!
Did you offer her any advice? Perhaps you could mentor her, at least while she's doing the game for your grandsons' team. As several people have said there aren't the mentors to go round so offering advice to her instead of just saying that she was hopeless may be the difference for her. This may have been the game where she decided if this was for her or not, and a friendly face instead of all the snarling ones may have helped keep her in the game.
As Rusty said, I was shocking in my first game. I called for an offside before remembering I was the one making the decision! I also made L3. We all have to start somewhere, and as Referees we all know how hard it is when the teams are baying for blood. At whatever level we are at the hardest thing to deal with is the abuse we get. There's another page on the site today about two managers fighting at U7. Just because it's youth doesn't mean there's no grief. It's working it's way down the levels.
We all have games where the teams and spectators think we've got everything wrong - I had one yesterday. I know I got most of it right, just like always, but the teams feel that if it's against them / they don't understand it / don't think the game needs it then it's wrong. As Referees we should be supportive of people who have the guts to stand up and make the decisions, not slag them off when we think they're wrong. If we helped them then maybe they wouldn't get so much wrong because they wouldn't be so worried about everyone moaning all the time.
My elder son did the course many years ago. He was actually a good referee, but he hated it because he is too nervous and didn't enjoy being moaned at when he made decisions people disagreed with. He could have got to a pretty high level on ability, but he felt all on his own, even though he knew I was there for every one of his games. He stopped doing it and I don't think he'd ever go back to it, not because he didn't enjoy it, and he was certainly good enough, but he didn't like the fact that people got on his back so much when they disagreed with his decisions.