We allow our 4 year old to do it too.
(Luke may or may not have a few issues that for some reason no photos of him were taken, yet he was the reason we went.)
Sometimes Mike and I get carried away in conversation.
We don't keep our eyes on all our children all of the time.
Sometimes nice people get our attention to tell us our child is bleeding.
We are greeted by a bloody faced child and have no idea where the blood is coming from.
Sometimes Dad takes charge and gets it *cleaned up* with borrowed napkins before Mother takes a picture.
We figure out the blood is from a big nose bleed after the nose crashed into the handle bars.
Sometimes Mike thinks blood all over the handlebars is cool and insists I get photos of it.