How does Scrabble letter distribution work outside the US?

Is Scrabble as popular in other countries?

For example -

The letter ‘u’ shows up in comparatively more words in the UK (colour, favour, etc.) than in the US. Does the UK Game have an extra ‘u’?

The German letter ß isn’t used anywhere but Germany. Is that represented in German Scrabble?

Does the French Scrabble have accents on vowels? Do they make a difference? What about Spanish diacritics?

And what about languages like Polish, Icelandic, and others that use a mostly Roman character set, but with various additions?

And let’s not even get into Arabic, Hebrew, Persian, Thai, and various Indian scripts.

How is letter frequency handled?