thats pretty much what I have seen in my time of ordering them for my little lad. He generally loves only froth from me, followed by a top up of milk once he has finished it. He is always the first to place an order a chino when I offer coffee at home. ::)
He has come to expect some warm milk in the bottom when we are out. Once he was scalded by a very hot cup of steamed milk in the past, so a warning to take care what is given to a young child. I know the sensible people here would think about that, but obviously not everyone does.
I do not expect to be charged for one though. I figure if I am ordering multiple coffees for adults, it is a matter of courtesy for the host to stick a bit of froth in a little cup for a toddler. It takes more than a bit of choc powder and a marshmallow to make a $2 charge seem worthwhile.