The biggest problem is that you have ~~stupid people~~ less discerning people who think "I'm not a camel" and because they know they are not that thing assume that they are safe or that others know they are not that thing.

Not to mention that you shouldn't have to prove you are a citizen; the government should have to prove that you're not.

Without due process, the government doesn't have to prove anything. It can just make the claim, and then act on the claim.

There is a 1987 paper tracking the joke through history: A Romanian Political Joke in 12th Century Iranian Sources by Mahmoud Omidsalar (Hat tip)

This is the 12th century version (Hat tip):

A fox was running, grieving for his life.

Another fox saw him in such a state

And asked: "Please tell me, brother, what is wrong?"

He said: "The king is hunting donkeys here!"

"But you are not a donkey - so why fear?"

He answered: "That is right; but, oh!, these men;

They do not know and they cannot discern.

They think that fox and donkey are the same!"

https://archive.org/details/AnvarisDivanAPocketBookforAkbar/page/n119/mode/2up

Allegedly, expressions along the lines of "to prove you are not a camel" are common in Poland and Russia for tedious bureaucratic demands.