I strongly disagree. You should always write rules under the assumption it will get in the hands of the worst people. If there is a 'become god-emperor' lever in your supposedly democratic government system then it is a shitty system.

No careful rulecrafting can survive the worst people being in charge.

That’s the topic of the Federalist Papers. It’s been working for 2.5 centuries.

Maybe so but what here really would've prevented this? The information involved is necessarily public: bank details and credit card numbers need to be shared otherwise why have them?

Writing a rule that says the government can't do this is just the government writing a rule it can simply remove it ignore when inconvenient.

The banking information belongs to the account holder and the bank. Google knows it by coincidence but should not share it because it isn’t theirs. If the government wants to know my banking details they can ask my bank. If they can’t figure out who my bank is they should get better at investigating. This approach is just exploiting Google’s wide reach.