Europeans were howling in rage at negative interest rates. In some banks, for a while, people with 100,000 were getting hit with negative interest rates. In other words, if you left 100,000 in your savings account, at the end of the year, you would have 99.250 or 99.000. After a wave of very vocal protests, that was raised to a minimum of 250,000, but it still encouraged many people to spread their saving around several banks to avoid the punishing.
European banks now make it very difficult to deposit or withdraw even modest amounts of cash, and even then they record everything. If you have a 200 bill and you want ten 20 bills, they take your ID and list the transaction alongside your bank account number--to combat money laundering, they government says, as if that made any sense at all. European governments take all sorts of high-publicity measures against "money laundering" except for measures that really would limit money laundering (real money launderers shoot back, private citizens wanting five 20 euro bills do not). Nonetheless, many EU citizens go through the paperwork, and prefer to use cash. European governments are drowning in their own tsunami of paperwork, recorded phone calls and information collected on private citizens anyway. The bad guys laugh all the way to their villas on the Dalmatian coast, since money laundering is not conducted with 200 bills or 500 bills or Krugerrands. It is conducted with laptops and phony taxi companies, video game parlors and pizzerias. These low key operations dutifully turn in mountains of 10, 20 and 50 bills to the bank every day, fully reported and taxed. Hardly any taxi fares rode, hardly and video games were played, and hardly any pizzas were sold, but that drug money has to go SOMEWHERE, and the governments turn a blind eye, because THOSE bad guys shoot back. The old lady selling a Krugerrand does not.
So, if the banks stop charging their customers negative interest, those customers' incentive to spread their accounts across several banks to avoid hitting the negative interest threshold is gone. They will go back to leaving their savings in one single bank account. This will be welcome news to tax authorities, who won't have to audit ten accounts per upper middle class person instead of one.