Ah, Hindi. That's not strictly about age, though, is it? It's as much about relative social status (though age may be one factor in that). So you'd potentially say आप to a younger person than yourself in order to show proper respect, e.g. if they're an important official or similar figure.

I miss some things in English too:

- Not being able to specify in one word if a friend is a male friend or female friend like amigo/amiga in Spanish.

- The words for friend, boyfriend and girlfriend are too similar. While in spanish amigo/novio, amiga/novia are completely different.

- Not having one word descriptors for someone's ethnicity, as those have to be used very carefully or can't be used in English ag all. Like "Avisale el chelito que la zarca lo está esperando para ir a la tienda del chino" (common in my dialect of Spanish). "Tell the white-person that the light-eyed-person is waiting for him to go to the store owned by the asian-person" (very unnatural in English).

I'm curious, in which context does it matter?

I know that this is a very cultural thing - as an example here in France it's completely unimportant, you would simply address kids (or at least younger kids) a bit differently than adults, but appart from that the age difference does not matter at all (and culturally it's important to know whether someone is a kid or not, because, to simplify, kids are legally "irresponsible", cannot vote, purchase alcohol, etc and some adults must have legal authority over them)

Sadly that can’t be done, son.