its only a 4 or 6 digit number and you rarely have that many of them unlike passwords so i just remember them. its not actually that much of a stretch for most

its only a 4 or 6 digit number and you rarely have that many of them unlike passwords so i just remember them. its not actually that much of a stretch for most people to do, if you think back to the days before you carried a mobile with you at all times you likely knew at least 10 peoples phone numbers by memory so memorizing pins is easy