Corporate data miners care if you reuse someone else's registered phone number.

The cashier doesn't. Their incentive is to keep the checkout line moving. Sometimes they will even offer you a card at the register to get you a discount (not sure why).

The manager's incentive is to keep customers content and returning.

BTW, what is the significance of that specific phone number?

> Sometimes they will even offer you a card at the register to get you a discount (not sure why).

Because they are told to do so, to get as many customers as possible use the card. My wife automatically answers "no, we haven't got any and are not interested, thanks".

> BTW, what is the significance of that specific phone number?

It's Pi :)

How does having all the customers use the cashier's discount card help the company at all? I've heard the opposite in many stores, where they prohibit the cashier from doing that since it's giving away money (and loyalty points to the cashier) without collecting any data.

I misunderstood... I meant a newly issued loyalty card, not cashier card.

Cashier card is something I don't understand either. Maybe some database somewhere with NOT NULL, so that problem was solved by issuing cashier cards?

> They might notice the pattern it makes while they are typing it.

that's only a problem if the minimum wage worker behind the counter cares, which I doubt.

Bingo. They're not being paid any more or any less per hour if you get a discount. Why not do something nice for people?

Plus those cards often have points or other rewards, e.g. spend 2400 points and get these cucumbers for $1 off, so it's a win for them too.