No. There is a big difference to "they already know" and/or they "could trivially find out". Even if the latter may be true, the former is not. The government does not have direct access to personal bank account ledgers.
Pretend for a moment that Merrick receives a piece of memo from a subordinate that incriminates you in some form of bank fraud. Of course Merrick personally doesn't know anything about your bank account. Nobody has both the information and a brain big enough to store it. Hell, I have to check my own bank account regularly because I keep forgetting exactly how much is in there and it's my own money!
If something came across Merrick's desk and it convinced _him_ that it was worthwhile to investigate, do you really expect other than delays waiting for signed papers before he got the information he wanted? Do you really think there's a difference to Merrick whether he gets that information in 60 seconds by logging into your bank "as you" and looking at it, or whether he waits a few days and gets hand delivered a piece of paper by a bank's legal team?
[1] U.S. Attorney General and current chief law enforcement officer for the nation
There's some decentralization within the government also, if one branch wants something from another it (ideally) has to go the courts route too, it's not that every federal employee can just access any government records on a person, (at least in theory). If there's someone powerful enough taking interest in you to override that, I doubt a private bank is going to be a major obstacle.
I mean courts themselves are technically part of that system too. I am as cynical as the next person regarding government overreach, but I see little protection from a multi-national banking entity entangled with the government for decades in all sorts of ways.
If it was as 'easy' to start a bank as an ISP in the 90s, I could see it.
I don't think the Fed is "government" in the 4th amendment sense that it can just get information about you without a warrant, is it?
In an unrelated law, this is the reason child abuse reports from ISPs go to a private company called NCMEC. It's so law enforcement won't have automatically have access to private data in the reports without legal process.
There’s a massive difference between the data being theoretically available somewhere in your organization and “trivially” accessible vs actually being able to run a query (let alone the work to actually run the query).
With that said the unbanked crisis is severe and there are big societal benefits to insuring everyone has a checking and savings account. There’s no reason robust safeguards can’t be built into the law establishing the Bank of the United States (Third time is the charm!).
If you don't do this, the money supply gets a lot smaller.