I used to work in banks (in the UK) and they took what might seem like fairly draconian measures to help combat insider fraud threats.
At one bank I worked at you had do use their banking services for your main account (where your salary got paid in) and the bank’s fraud staff had a right of review over your account activity.
Branch staff (and others with access to customer funds) were obliged to take at least one 2-week or longer holiday each year, as it allowed for reviews of your work while you weren’t there and also made frauds harder to maintain as reconciliation processes carried out while you were on holiday would catch things.
Even with that there were cases of insider fraud still, access to money is a big temptation. (As an aside one reason I steer clear of the cryptocurrency space, the exchanges are like totally unregulated banks effectively, access to lots of customer funds and probably not great internal fraud controls)