Exactly.
As most people PRIOR to 1920 were illiterate.
Wikipedia:
So if a PC does not pick up the skill of literacy, they can not read in my campaigns. And even then, they have to be specific on which language.
I achieve much the same result via different mechanics; also not all languages (particularly "monster" languages) even have a written form. All arcane casters, however, are automatically literate in their native language, otherwise how could they write/read their spellbooks?
So having a map written in Chinese and you can only read English... guess what, you can't read the notations.
True, but I think you'd still be able to recognize it as a map most of the time. And keep in mind there's also magic that can help, in particular the Comprehend Language spell.
And even then, if you have never seen a map, how are you going to be able to understand it?
Hard to imagine a PC who's never seen a map, particularly after a few trips into the field.
There are:
- Political Map. A political map shows the state and national boundaries of a place. ...
- Physical Map. A physical map is one which shows the physical features of a place or country, like rivers, mountains, forests and lakes. ...
- Topographic Map. ...
- Climatic Map. ...
- Economic or Resource Map. ...
- Road Map.
etc.
There's also schematic maps, representative maps, pictorial maps, line maps, etc.; so yes, they can vary greatly. Depending on what's being mapped, they can also vary immensely in their accuracy.
Your PC is not automatically literate and can read a map.
I completely agree that not all PCs are literate. But even then, illiterate people all the way back to Neanderthals can still draw and interpret pictures - and a map, in its basest sense without any written labels, is a picture.
Nothing's automatic, of course, but I'd always give an illiterate PC a half-decent chance of recognizing something to be a map and a much smaller (but rarely zero) chance of being able to interpret any of it.