The government can access the bank logs, but it doesn't have an automatic channel to do so for everyone at once. Making it easier for the government to spy on its citizens definitely is an issue.

I wouldn't mind such a service being opt-in for citizens but mandatory for companies to support.

Surely, in theory at least, they require a subpoena/warrant. Perhaps I am hopelessly naive.

They don't need a subpoena/warrant for data that the company chooses to sell the government. It's not your data, but data about you owned by the company. The government can ask a bank or netflix for all their customers data or even for an online portal that gives them unlimited access to whatever they need in exchange for cash and plenty of companies welcome the new revenue stream. (see for example https://www.nbcnews.com/tech/security/us-government-buys-dat...) This isn't limited to the government buying up data either. Things like access to real-time GPS location has been for sale from every major mobile carrier