1. Fees at most banks are high. (A basic account with no transactions typically have fees of several dollar per month).
2. If people are moving away from physical cash, its because of security concerns (theft and robbery), not liquidity.
3. Most transactions are done by credit card, debit order or Electronic Fund Transfer (EFT). EFTs are done between numbered banks account. Mobile to mobile phone transfers are still very rare.
4. People are stubornly loyal to their banks. If root fails, it will be cause of this.