Whether it's the printed page or traffic signs. I think the court will agree that these laws, like civil laws, ought to be obeyed. For example, some letters have little appendages called serifs on just about all their corners . Research proves that typefaces without serifs are more difficult to read. Tests also show that black type on a white background reads better than the reverse.
Tests indicate that upper and lower case letters read better than all capital letters.
Always use upper and lower case. Furthermore, it's been proven that letters on a colored background are difficult to read. Always use proper punctuation. I rest my case.