The digital economy is such a big industry and I've read some quotes in the past that if a business is not on the internet, soon, they'll be out of business.
No, that's not entirely true. There are cities where people aren't technically advanced or the highest percentage of the population is 30-40+ and have no idea how things work online. If in this particular city, you create an online shop or a website, that will be a waste of money, time and resources because everyone is old-fashioned. The Internet needs businesses that are in capitals and in advanced cities, like Barcelona, Madrid, Berlin, Munich, Milan, Dublin, Oslo and etc.
We can say that's some of the exceptions but if we're going to talk in general, most of the countries now are connected to the web and they can have their digital economy there. And as a businessman, I'll consider if it's going to be a good addition to having a website for my business but you're right that if my target market is my local area that doesn't use mostly the internet then it makes no sense at all. But if we look at the whole thing with the global competitiveness now of many service industries, you'd see how huge it is and those few people or cities or rural areas that you're talking about having no connectivity at all are just a few and most of them are irrelevant for the digital economy. And with some tools like Starlink or any type of other the same satellite dish tool, even in those areas that are not serviceable by the ISPs can have their own share to the global digital economy by not being a businessman but as freelance workers.