You know the one. In every weekday at ten past eight, same order, pays with the same card, has been coming for three years. Says "no thanks" to the stamp card every time, pleasantly, and you have stopped asking. They are your best customer and they are not in your club.
This is worth thinking about properly, because the regular who never joins is not one person. They are three or four different people with different reasons, and the same pitch fails on all of them.
The one who does not want to be marketed to
The most common reason, and a fair one. They have been burned by a scheme that turned into a daily email. They assume joining means noise. Telling them you will not do that is weak; everyone says that.
What works is showing them the deal is small. Counter Club's join page says three things: the shop name, how many stamps earn the reward, and what the reward is. The only thing it asks for is a mobile, confirmed by a code. First name and email are optional and say so. There is no password, no app, no account. If you are on the Free plan there are no campaigns at all, and you can say that truthfully.
And if you do send campaigns later, every one carries their own opt-out link, and replying STOP to your number works. The way out is in the first message they get. Someone who refuses schemes may well join one where leaving is obviously one press.
The one who does not want to give a mobile number
Less common than you would think, but real. They see the number as the thing that gets sold.
Be straight: the number is the card. It is how they get stamped without carrying anything. It is used by your shop and nobody else; no other shop can see it, and it is never sold or shared. If they would rather not, that is the end of it. Do not push. A regular who feels pushed stops being a regular.
The one who is in a hurry
They are not refusing, they are late for work. Every pitch at 8:10 is a no. The same pitch at 2:30 on a Thursday is a yes.
So do not pitch at 8:10. Ask when the shop is quiet, or when they are waiting for something anyway. The join takes about as long as a coffee takes to make, which is exactly why the QR goes next to the machine and not at the till. Let them do it while the milk is steaming. Or hand them a card with the QR on it and say "scan it when you have a sec". They often do, on the walk back to the office.
The one who does not see the point
They are going to come anyway. Why would they want a card? This person is honest and you should be too: the card is a thank you for what they already do. Twenty-five free coffees a year for the person who buys two hundred and fifty, on a ten-stamp card, is not a trick, it is manners. Say that. Then stamp them.
What not to do
Do not add them yourself. Counter Club does not let you, and that is not an oversight. A member who did not join is a person who did not agree, and the first text they get from you is the end of three years of goodwill. The join page exists so that every number in your club was typed in by its owner and confirmed with a code. Your regular is protected from you by the same rule that protects everyone else.
Do not stamp a card for them and hold it behind the counter. That is the paper-era version of the same mistake, and it ends with a drawer of cards for people who never asked.
Do not make it a thing. One ask, maybe a second one when the shop is quiet, and then let it go. They know the card exists.
When they join anyway
It happens more than you expect, usually months later, usually because they watched someone else get a free coffee. The join page is the same for them as for anyone. When they come up as a new member on your Members page, stamp them for that visit and say nothing more about it. They were always your regular. Now they have a card.
The regular you are not seeing
While you think about the one who refuses, think about the ones who joined and stopped. The Members page does not show when someone was last stamped, but you know the faces you have not seen for a while, and a member who joined in March and is still on seven stamps in October was a regular once. Something changed. You do not know what, and a card cannot tell you. But a quiet, occasional message to the club, with real news in it, reaches them the same as everyone else. That is the person the campaign is for.