In reply to Currency symbols:
The thing is, if someone wanted to use the Baht symbol with Thai numerals, they'd use a different font (which supported Thai). My market would be people writing in Latin alphabets, so the symbol would only have to 'work' in this context. I lived in Japan a year or two ago, and they have their own kanji form of Yen (円), but in Latin fonts, we use the standard ¥ symbol. I think this is the same kind of situation.