Experience is not truth; a large part of people's "experience" is their own beliefs.

Heck, a large part of people's "experience" is fiction.

For instance: By the age of fifteen, if there are no doctors and nobody chronically ill in your immediate family, you've likely spent more time watching and reading fiction about doctors and medicine than you've spent discussing medicine with actual doctors. So your ideas of what doctors do are going to be based more directly on fiction than reality. One consequence of this is that there are a lot of common false beliefs promulgated by medical fiction. (Warning, TVTropes.)

For that matter, I suspect many fifteen-year-olds have heard more lawyer jokes than they have heard sentences spoken by an actual lawyer other than a politician. (Though one can hope they've taken more of an impression from Atticus Finch than from kill-all-the-lawyers jokes.)

(And yet, many fifteen-year-olds decide to become doctors ... and lawyers ... and other professions whose reputation and habits they have learned about chiefly through fiction, jokes, and stories rather than through observation.)

For that matter, the claim that "the joke is more likely to resonate with the audience if it corresponds to their experience" implies that the erstwhile popularity of jokes about Poles being stupid and impractical was good evidence that Poles actually were stupid and impractical.