You cannot just exclude those people out , cash has been there for ages and it is right only to keep it in the following future because let's be honest guys 7.53 billion is the population and only 3.1 billion active smartphones are registered (considering how one person can own as many as they want) so more likely more than half of the people on Earth still live by the old times.
You know what's interesting with statistics, that you can play it how you want with numbers.
For example, you have shown how 3.4 billion people don't have a smartphone and that would put everything on hold...
But if we were to exclude India from this, the number would drop to 2.4 billion, and you have to admit that nobody is thinking India will go cashless first.
In western countries, the smartphone penetration rate to nearly 80%, and if we take into consideration the natural change in population structure every year around 1.3% of the old population is no more and is replaced by a new generation. And besides, the new technologies don't care about what's happening in poor countries, do you see electronics manufactures stopping the production of coffee makers, microwaves, air conditioners because half of Africa is not affording one?
Yeah, right now, banning cash would be a problem even in advanced countries but in 10-20 years your kids will laugh at you how you were counting piece of paper when buying bread and the cashier was counting your change and you were walking with metal scaps in your pockets
The same happened with cars around here, nobody believes you're going to have that many old people living in the countryside and owning a car, then it was the internet, my grandma would probably laugh right now if she could see her daughter (my mom!) checking the weather on an app and not by looking at the sky.
Some of the people who still stay in cash transactions might be the people who were scammed, hacked by the digital crooks before and started having traumas using their cashless payment methods.
With a card, you always have the option of a chargeback.
Getting mugged in an alley or a bus station....there is nothing you can do.
I wonder what's more traumatic, seeing that somebody bought 2000$ of sex toys with your card and you have to call the bank to cancel the charge or having a knife at your throat and losing all your rent money.