I am not a fan of over regulation but bucky balls are fairly unique because their danger is not obvious and can not be communicated by it's form. They are too small to have a warning or graphic on them. I've seen a lot of bucky balls, I have NEVER seen the box with warnings (people throw it away).
A small sphere (as opposed to say a kitchen knife, or a jart) is almost the definition of safe. Even swallowing one is not a horrible outcome. They are not poisonous. What I'm getting at is it's a very unintuitive danger. It's only when multiple are swallowed that it becomes deadly.
So take yourself out of your obvious nerd minds and try to look at this objectively. The personal responsibly arguments hold together in the case of me the parent buying them and me the parent allowing my own toddler to eat them. But it's a big world out there. Your kid could take 2 off your desk. Would you even notice (or do you keep your bucky balls locked up in the gun safe)? She brings them to school. She leaves them on the floor. My younger kid comes by puts them in her mouth. Is this my neglect as a parent?
Insert almost anything else into that scenario and the outcome is better because it's either larger, more obviously dangerous, or problematic but not dangerous. For example:
Knives/tools/etc- Most reasonable adults and even kids above the age of 5 would intervene or tell someone "Hey, Bobby's trying to eat that knife"
Bullets- If you saw a kid playing with a box of bullets, even a strangers kids, hopefully you would intervene. But even if the kid ate one it probably wouldn't kill him.
BB's, Coins, Legos- Kids have been swallowing these for years and while it's unpleasant, they survive.
The problem is they are small, numerous, easily transportable, and not intuitively dangerous.
