The first digits are a header identifying the type of the card, (visa, mastercard...) and probably other characteristics.
The main problem is that in Japan everybody has like 5 credit cards, because every big company has its own financial branch and issues cards (maybe to profit from a "reservoir" effect of the accounts?). So you have a credit card linked to your clothes shop, one from your supermarket, one from Rakuten (Japan's Amazon), etc. You get points when you buy things from the company linked to your card. I don't know how it is in US, but it certainly isn't like that in France for example.
"everyone" may be a bit extreme. There seems to be a national goal of going more cashless, but right now they're one of the most cash-based countries: https://www.statista.com/chart/19868/share-of-cash-payments-... Japan had 82% cash transactions compared to 14% in South Korea. From personal experience it's relatively normal to find a food place in Tokyo which has no card reader at all.
Everyone has a bunch of cards, they just don't use them.
We have a credit card for a mall, only for the free parking at said mall. We never actually pay anything with it, only scan it in the parking garage.
That said, cashless transactions have gone way up in the past year though, though the introduction of PayPay QR code payments (which means that waaay more small mom&pop stores accept a cashless payment system since adopting it is basically free), the government 2-%5% cashback cashless incentive that ended earlier this year, and the coronavirus.
It will be interesting to see the new cashless usage numbers next year.
I was going to agree it's a lot... but then realised every one of my grocery gift cards has a PAN attached, which means I'm going through 2-3 numbers a month myself. (Not in Japan) Then again, I expect the shop to recycle those faster than Visa.
> The main problem is that in Japan everybody has like 15 credit cards
This is a fascinating departure from my expectation, because when I was in Japan, I distinctly noticed that credit cards were not accepted everywhere. One could load money into Suica/Pasmo cards and use those at convenient stores, but I learned that carrying cash was imperative -- Japan seemed very much to be a cash-oriented society.
No your observation is correct. Japanese people have many credit cards but also pay a lot in cash, and small restaurants for example do not accept cards.
So they are now in the absurd situation where they do not have enough credit card numbers, but still many shops do not accept card payment.
(I edited my previous comment for realism: it's more 5 cards/person than 15)
You forgot that these 16 digits have a structure, with the 4 or even 8 first ones being determined by the type (visa, mastercard) and the bank/country, etc.
"The first six digits represent the country, brand, and the type of card issuer and other elements". The last digit is a check digit so it's actually only 1 billion.
