Why Aren't These More Common?

Baby seat on the back of a bathroom door.  How many times, in kid friendly places, have I balanced a baby while attempting to undo my pants and use the bathroom?  Or better yet, skipped using the bathroom altogether because of not having a way to hold the baby or corral a toddler who wants to crawl under the stall door?    

 I would love to see more of these (particularly in train stations and airports)!