This. All of these things are part of the body of law, in particular the Bank Secrecy Act of 1970 and the various extensions and acts (like the patriot act) that build on it, to take the US as an example.

Whether that is constitutional or not is a good question. You say that citizens are innocent until proven guilty. In fact, it's not citizens, I think it's very important to note that most constitutional rights (except very few, like voting rights) apply to 'any person', not 'any citizen', and the supreme court has in the past always used this interpretation.

But as for the substance of a person people innocent until proven guilty, so what? Just because a person hasn't been proven guilty yet, does not say anything about the legal or constitutional right to prevent monitoring. i.e. it's completely okay for the police to set up a speed sensor on a highway and monitor if someone is breaking the speed limit, right? Just because that person isn't proven guilty, and is thereby innocent, does not say anything about the right to not be monitored.
There are civil liberties like the right to be safe from unreasonable search and seizure. But that generally applies to things like ones house being entered and searched, or a person being frisked. That is sometimes called upon. I don't really think it holds up, too well, because it doesn't make any mention of things like financial records originally.