That's an unhelpfully restrictive definition of illusion that is itself illusory. An illusion is also:

A sensation originated by some external object, but so modified as in any way to lead to an erroneous perception; as when the rolling of a wagon is mistaken for thunder.

The text is hidden or revealed through a change in perspective. That is the illusion.

How many knife fights have you been in?

How is a zig-zag numbering any less valid than any other method? Your mapping a two dimensional space with what is essentially a line. Sometimes it doesn't make sense for there to be discontinuities in the numbering, as one would have to do if the numbers always incremented in the same direction. Would you prefer that the numbers follow the path of a Hilbert Curve?

To answer your question though, surveyors have been using this method to number sections of land for much longer than you or I have been alive.

Knives suck as a defensive weapon though. I'd rather be robbed than be involved in a knife fight, even if I was the only one with a knife when that fight started. Carrying around a knife for defense if fucking crazy!

Batman

Whenever I'm forced to use windows, show file extensions and show hidden files.

No, not against just him, against the entire party supporting him.

More like working class traitor.

Give em The Harkness Test

I don't ask people about their politics. I just act like true things are true, e.g.: human instigated climate change, COVID, the efficiency of a single payer healthcare system, a oblate spheroid earth, and the moon landing. I'm politely understanding of the flaws in their world view, but I NEVER pretend that any of it is even up for debate. You can balance not being rude with not backing down from the objective reality you live in by showing an genuine fascination with their weird cult beliefs.

Conspiracy theories, religion, myths, and magic are all very comfortable fantasies that wither in the face of the existential dread from understanding that the universe is horrific and absolutely indifferent to your personal suffering. Being excellent to each other and maintaining faith in the potential of humanity (tempered by knowledge of our depravity) is our only hope of survival both physical, philosophical, political, and spiritual.

Ok, sorry that turned into a rant. This shit matters though, so not that sorry.

"Sensors" sounds like a magical solution that hasn't been thought through, but the marketing guys already sold it and won't listen to the engineers explaining how difficult it is to actually build such a thing.

I'm no nationalistic fanatic of the flag, but is it really so difficult to understand that the flag is a symbol?

Obviously each flag, be they for nations or other groups, represents more than just a piece of cloth to many people. Taking offence at someone else's identifying with what a flag symbolizes is not okay. But, I tend to look skeptically at worship of any kind of idol, be it flag, cross, or text. That still doesn't mean it's okay to hate or persecute people for their beliefs, even if they appear silly to you and as long as they don't hurt others.

One group can demonstrate their respect for the nation by physically following some rules around the flag and others can demonstrate their loyalty to their ideals of the nation being violated by flying the flag upside down or burning a flag.

A flag or banner is not just a piece of cloth, never has been.