> Note that I do not use black, but a wide range of near-blacks. MS Paint's fill tool only fills the exact same color so using a range of near-same colors allows you to use the fill function to erase errors without impacting other parts of the drawing.

Wow, what a workaround for not having layers!

At junior high, this guy sitting close to me would spend all lessons where a computer was available to draw Scania trucks in paint. Somewhat similar in style to this random one I found by a search now, but sometimes even at an angle with perspective https://www.flickr.com/photos/145204045@N05/31629814288