I just looked through my wallet and Amex, Visa, MasterCard, and Discover all have the same date format, and for MasterCard three are from separate issuing banks

I just looked through my wallet and Amex, Visa, MasterCard, and Discover all have the same date format, and for MasterCard three are from separate issuing banks, one of which is a debit card. Not questioning you, but what's the rule? Do you have any examples? Is it a function of the processor or the bank?