There are 'sucker lists' of those who have already been scammed. there are as well lists of people who answer, and are therefore worth a punt.
The calls are automated so even if there are 2 replies per 10 000, it is still worth doing it. By chance with lots and lots of tries ( takes up a Poisson chance distribution) there will be inevitably people who have JUST used their card and are expecting a delivery
alternative maff models are the predator prey equations - we are the prey as punters and the predators are the scammers. Both models dont work badly = represents the chances of success, and what happens to the prey ( they learn but have a loss - at least not dead) and predator ( they starve and so something else, but dont die) (Volterra Lotka)
If you accept that people get touched once but not again, then the covid model equations would work
yeah you pick the model you fancy ....