What do you mean they don't exist. I see them everywhere, indoor, outdoor, also every single school gym regardless of level is also a basketball court. I've lived in 3 countries here east & west Europe and this is valid across different places and cultures.
Huh weird I've never seen one in Netherlands or Spain. In the Netherlands it's not popular at all though we have a similar thing that is ("korfbal").
My school did have these basketball boards but we never used them and I'm pretty sure the room was not sized for them either.