They may do it, but it's against code, and they could be busted for it if it was found out. However, this is about policies and protocol, which denotes that it is a relatable issue and something that is concerning in terms of raising a child. If they cannot support a child, then perhaps something needs to be done about it.
It isn't about whether or not it is odd. It is, literally, against the terms that allow you to keep your child. If discovered, social services will investigate it and it will negatively influence them, that is that.