"Gallup first measured confidence in institutions in 1973 and has done so annually since 1993. This year's survey was conducted June 1-20.": "Now I am going to read you a list of institutions in American society. Please tell me how much confidence you, yourself, have in each one -- a great deal, quite a lot, some or very little." 73% said, "'some', or 'very little.'"
Looking at the historical data for that poll might offer some insight.
Until 2006, of those asked, around 50% had a "great deal / quite a lot" of confidence in banks (comparable to confidence in churches in that year, and better than confidence in the supreme court, public schools, newspapers, or the criminal justice system).
With the financial crisis 07/08, those numbers took a nosedive, bottoming out at 21% in 2012. They recovered a bit, but never really reached those previous heights.
We can see another small height of 38% in 2020, which declined again in 21/22 to 33/27%, coinciding with the covid-19 recession and 2021-2022 inflation surge. While banks may or may not have a direct impact on those crisis, in a time of financial hardship people will have more negative interactions with institutions that offer them credit, mortgages, etc, which may erode their trust.
Banks and bankers are not "popular". They seem to be making money (lots of money) without actually making anything.
And that's when things are going well, when things go badly people can loose their life savings.
These polls tend to turn into a measure of popularity.
So it is not surprising that people rank banks lowly on any particular scale. It matters little if you ask if they are "trustworthy", "socially useful" or "environmentally friendly" (!) If you ask people to say good or bad things about bankers, they will say bad things, because they don't like them.