Not challenging your claim that East-on-top is common (since I have no idea), but: it's called the orient because oriens is Latin for rising, and the sun rises in the east. Many other languages also have a word for east based on their word for rising. For a cursory reading, check out the Wiki article on the etymology Orient: https://en.wikipedia.org/wiki/Orient#Etymology
Which points North, unless it points South; Chinese maps traditionally put the South at the top.
Here's an example of such a map, of the form known as "T and O": https://en.wikipedia.org/wiki/Early_world_maps#/media/File:D...
It's interesting to me that, as moderns, we barely recognize such a stylized image as a map.
But there's a map in the public library of my hometown, showing it in 1890, in which the Old West Side is at the top of the map. So I'd guess that non-standard orientations were more common than they are now.