My cat will play fetch with those little sparkle balls too. But she absolutely will not drop it at my feet. Instead, she’ll drop it a yard away. Always. Then I have to go get it to continue the game. Which I do, because I enjoy the game.
You have your cat well-trained. And my cat has me well-trained.
No training involved. He just has expectations of human behavior. If he drops that ball he expects his humans to throw it!