The rationale for bail out the banks previously was that the retail arms (what you and I use) were so intertwined with the commercial arms that allowing the commercial part to fail caused the loss of everyone’s money. Regulation was introduced (at least in the UK. I don’t know about elsewhere) that ring fenced the two from each other, making future bailouts unnecessary. The commercial arm would shoulder the risk of its own investments.

Doesn’t stop corrupt politicians bailing them out though.