Why do parents push their kids to Santa

I was at a shopping centre yesterday and I watched the little kids getting their photos taken with Santa, big mistake, I got so upset to see the fear on some of the kids faces, some were literally screaming, I am afraid I could not do that to a child, and what for, a photo and believe me some of those photos are not going to be nice, maybe good for giving to their son or daughter on their 21st birthday maybe....why do parents do it???