Isn't that why kinder eggs have a rather large plastic shell that contains the toy? I haven't seen one in years, but from my memory, even an adult would be unable to consume - or swallow enough to choke on - the plastic shell.
it is conceivable that someone takes a large bite that causes the inner container to open up and let small pieces of plastic fall out into the mouth.
but the law was not written for kinder eggs. i can imagine much more dangerous products.
i believe in germany they approach this with better product testing. instead of blanket rules for what is allowed and what not, individual products are tested for safety, and get regulated based on that.