What age do kids learn to tie shoes

I know a person who’s child is in 2nd grade, she is 8 years old and doesn’t know how to tie her shoes. Is that normal? I think I was 6 when I learned and with my other friends who have children they learned around 5 or 6 years old also. This child’s mom isn’t the best mom either, not going to go into detail about that. But I’m just wondering if by 8, in 2nd grade they should know how to tie shoes?