You are presuming more branches were opened up because banks were cheaper to run. When you look at the growth of the economy since the ATM was implemented, it makes sense that more banking services were required.

Of course, the number of banking personnel has been dwindling down, especially on the investment banking end.

And I wouldnt be so quick to point to the financial arena as a means to discount the point of the article since fintech is far outpacing other technological developments. The only reason why the banks still have so many branches is because they own the real estate. After the 2009 collapse, much of the buildup in terms of branch expansion was stopped and, along with it, the number of tellers..