Just using unicode would be a disaster. It still has to be constrained and the law should and does define what characters are allowed. If company names can have

Just using unicode would be a disaster. It still has to be constrained and the law should and does define what characters are allowed. If company names can have emojis or multi-layer stacked diacritics or text direction changing between left-to-right and right-to-left in the middle of the name, or an invisible word joiner character, nobody will be able to make sense of them. Names are for humans, so they have to be in human language.