The problem isn't about how difficult it may be to open an account. The problem is that banks become gatekeepers for the ability to exchange legal tender for goods and services.
I could write an entire essay on the problems this causes if cashless business becomes wideapread. But a few highlights include:
* A positive feedback loop will form due to less cash being accepted => less cash circulating => less reason for businesses to accept cash
* Banks able to de-platform individuals and lock them out from access to life necessities
* Governments likewise able to de-platform individuals as a neat new way to oppress dissidents and undesirables
* The telco backbone of a nation becomes a one stop shop for a decapitating attack. Telco is also one of the first utilities to fail during natural disasters
* Impossible to purchase goods/services without it being logged, surveilled, and used to manipulate you with individualised advertising
* Once cash circulation drops below a critical point, opening or operating a business will not be possible without accepting card payments. That's your plumber, the kid who walks your dog, anyone offering any goods/services. Banks are now in control of who can receive money in addition to who can spend it.
* Ditto for p2p transactions
Anything that threatens the universal acceptability of legal tender should be viewed as a national security threat.