[Phil] I think Hollanders call the Netherlands "Holland" for the same reason that Englanders call the UK "England".

Because it's football. It's allowed in football apparently, according to Twitter last night while that very boring match was on. 'Holland' (as you probably know) is more accurately North Holland and South Holland, two of the 12 provinces in the Kingdom of the Netherlands. North Holland contains Amsterdam, and the Kingdom of the Netherlands used to be run from Amsterdam - possibly that's it. It's an historical reason.
BTW, Nederlanders call the UK 'Engeland'. All of it. Scotland, Wales and NI too. And on TV news programmes too, probably for exactly the same reasons.

[penelope] By curious coincidence so do Americans. I like encouraging them to say "Wales, England" or "Scotland, England" in their charming accents.

[Stevie] It works like a charm right up to the point where you try to buy a train ticket to that destination.

(pen) Do you mean to say the Dutch can't pronounce Machynlleth? Whatever next?