They’re mixing up a securities term (irrelevant to banking per se and cash management totally).
What they mean is getting an adviser who is bound to act as your fiduciary versus as a counterparty [1]. If you’re trusting your portfolio management entirely to a third party, they should be a fiduciary.
That said, people outside finance seem to make a bigger deal out of this than it is—in America if you’re a retail investor and you have a problem with a FINRA-member broker, FINRA arbitration will almost always side with the retail investor. Fiduciaries will tend to cost more (it’s riskier) and say no to you more; after all, you’re asking them to take decisions for you. I work in finance and couldn’t tell you which of my managers and advisers are fiduciaries because I double check what they say and limit what they can do. And this, again, has to do entirely with investments. Not banking.
More pointedly, this part is nonsense: "most people with under $2m in cash can't afford the bonded fiduciary services." What you want for cash management is yield (reward) and sweep (risk management).
[1] https://www.investopedia.com/financial-edge/0912/5-misconcep...
