https://www.ada.gov/law-and-regs/design-standards/2010-stds/
306.2.1 General. Space under an element between the finish floor or ground and 9 inches (230 mm) above the finish floor or ground shall be considered toe clearance and shall comply with 306.2.
Uniformity? I have no idea. Just its why its there for others at the very least.
One could spend the enegry to spin their own beliefs to demostrate their contradictions... but their cognitive dissonance will cause them to just dig deeper to maintain their world view... people have to have an open mind before any rational debates can be made.