ISO and United Nations adoption don't qualify Pinyin as an international standard?
Using Taiwan as an example isn't really relevant given that it's majority Cantonese speaking, and Cantonese is a completely different spoken language than Mandarin.
Edit: I'm a clown. I was confusing traditional Chinese with Cantonese. Not the same thing.
Hong Kong is majority Cantonese speaking. Taiwan is not, it's Mandarin (and to a lesser extent Hokkien and Hakka but most young people prefer to speak Mandarin).
You're right, edited my original comment to correct. Thanks.
A national standard, at best (in the PRC). In Taiwan, Zhuyin (Bopomofo) is universal, taught in schools and found on laptop keyboards, and romanisations are mostly following Wade-Giles rules. In Hongkong, Eitel romanisation is used even though their new commie overlords are forcing pinyin and yale canto down their kids' throats.