>>once you'd raided a hundred other sets for the extra zeds

There is a reason for those extra Zs. They're not really all Zs. There's a regular Z, and there's a Z with a line accent above which has a long equivalent of "zi" and that's how you pronounce it. Then there's a Z with a dot accent above, which is pronounced like the French J. There are more accented letters in the Polish alphabet, and if you take away the accent you can also alter the meaning of the word. So in a scrabble game you wouldn't be able to use one Z in place of another.

And there aren't a hundred of them. There are only 3.