For a good while the default US Intl keyboard in some Linux versions would give a ć instead of a ç for the combination c + '
Makes sense right? Except that made a lot of people angry and has been widely regarded as a bad move
Because Brazilian users were expecting c + ' to become ç
(And they had to use Alt Gr + c instead)
Because (for some reason) you don't have your "standard" keyboard - just the US ISO one
Some keyboards have an extra key (or maybe more than one) and hence can't be mapped fully with a US keyboard