I'm going to call BS on this argument. Though I life in what most would consider 3rd world country, everyone I meet here has a bank account and credit cards, even 70 year old farmers living in the isolated mountains of Adjara, as well as most high school students. The only thing stop someone from getting a bank account or credit card is stubbornness, idealism, or pure laziness.
I thought that too -- until a company I worked for expanded into the U.S. Setting up a payroll system for the new territory was eye-opening. We had to plan for a cheque-based delivery system (and weren't even allowed to use the word 'cheque' since the banks thought it was a miss-spelling that would render the document void so 'check' is became!). We needed a cheque-based system which we didn't have in Canada because a good percentage of the front-line staff didn't have bank accounts we could use for direct-deposit.
Wait there are groups who play with more than one PHB? Wow. That's something I've never seen, honestly. In high school, I played with a group of 11, in which only one of us had a PHB and MM. No one had a DMG. Same thing in my university group.
I've typically seen 4 PHB per 5 players in the group and a smattering of other books depending on how into the game each player gets and if the player considers DMing someday.