I guess it all depends on the frequency of such characters in the given language. For example, in french keyboards, we have dedicated keys for 'é', 'é', 'à', 'ç

I guess it all depends on the frequency of such characters in the given language. For example, in french keyboards, we have dedicated keys for 'é', 'é', 'à', 'ç' and 'ù', because they are incredibly frequent. On the other hand, 'â', 'ê', 'î', 'ô', 'û', 'ë' and 'ï' are less frequent, so they are generated using modifiers. I'm quite glad of that, actually, it would be really annoying if we had to keep using modifiers every two words. I know french people who use English keyboards, they just usually forget about accents totally instead of using dedicated modifiers.