I have some seedlings that maybe someday I will register. Meanwhile, I have named them. But when I talk about them in a forum or posting or real life, I state "garden named.....". I have purchased a few unregistered daylilies that were named, there are some hybridizers that will sell some like that. I do believe most will sell an unregistered daylily as a number, not a name though.
Even though I believe the cost for registering daylilies is very reasonable, especially when compared to the cost for registering the sheep & cattle I used to breed - it does add up.
I have no clue why others don't register their daylilies, I just know why I haven't. ~Jan