Bless you, I know what you mean, you can hardly believe it they are so easy to cope with!
I have always felt that children sort of instinctively know what their parents and grandparents can cope with, and so go that far, but not too much further!
For example my daughter slept like a dream as a baby, and I only had one totally sleepless night, ever. I think she knew Mummy had a breaking point if she didn’t get any sleep. But later in her life between say 11 and 16 she was hell on legs! At one time I said “you know I love you, and will ALWAYS love you no matter what? But just now, I dont LIKE you very much!” She also gave me worried times in her later teens and 20’s, but we got through. She’s a Mum of two herself now, they are 2 and 4, and she is learning just how hard the stages are. But no matter how easy or how hard they are, it’s worth it. So be grateful if yours is easy now, and brace yourself for when they are not, as it surely will come at some stage or another,