Oh, I disagree. Funerals are a lot less upsetting than the wake for some kids. My grandmother, whom I adored, died when I was seven. I didn’t mind the funeral, but seeing her laid out in her casket was an unpleasant, lasting impression; this however may have been exaserbated by the fact that people thought she was getting better so they never took me to see her in the hospital to say good-bye. (my last memory of her alive is running to tell my mom and grampy that she was throwing up blood - I don’t really remember the amblulance taking her away)
My parents realized that it was the wake that upset me, so when my great-grandfather died four years later, they left my brother(then age five) and I with an aunt when they went to pay their respects. We were both okay at the funeral the following day, though.