> I imagine that most (but not all) people reading this comment have savings that could cover either (i) an unexpected expense of $500, e.g. to repair the car they use to drive to work, or (ii) an unexpected one-off $500 drop in income, e.g. due to a gap between casual jobs.

And, even if they were short cash for some reason,they have both access to zero-cost (or negative cost, given rewards) short-term loans [0] and sufficient income after essential expenses to pay it off without resorting to loans with interest.

[0] e.g., currently zero-balance credit cards as long as paid off within the next billing cycle.