Normalise the data entered the first name, last name and organisation/household name, so they are Properly Capitalised.
For example, when you type XAV as the first name, it converts it into Xav.
It only works on specific forms, such as contact edit/add, public registration and contribution forms.
The rule is simple: as long as there is at least one uppercase char and at least one lowercase one (mixed cases), it's good enough and happy. It allows to deal with "Anne-Sophie" or "van Den Dach" or "Van Den Dach". Or nobility, or whatever. People are complicated. Bottom line, it avoid the ALL CAP name and the lowercase one too.
For imports (or api) it obviously can't suggest the case, so it puts the first letter in uppercase and the rest in lowercase. It's not perfect, but better than nothing.