For some recipes you need the yolk while the white is refuse, like sabayon for example. Of course if you have white leftover and don't use it to make merengue, you're insane.

Maybe for someone with a specific baking recipe in mind? One of the egg noodle recipes I like calls for about as many extra yolks as whole eggs. So I could probably just use these without waste or having to make a separate recipe to use up the whites. I've never seen this at stores near me either in the US.

For extra yolk-y mess to dip my toast in.

I assume somebody will pay for the novelty. Besides, if my summer raising chickens was to be believed those eggs are rare enough that it's not like there has to be a huge demand.

$$$

I think they are all sold to a company that wants them. Like McDonald's or something. No idea, not going to check either. Maybe a mayonnaise company, that would make sense wouldn't it.

Well, if a product doesn't exist in the European market, then it shouldn't exist at all. /s

The egg processor saw an opportunity to easily offer a novelty product. That's why we're talking about it at all: it's a novelty.