"Banks seems to have many layers of checking for potentially suspicious activity,..."

I don’t think so. I had this kind of incident and nobody from bank noticed it (60 euro paid over night 3:35 AM from central europe to fake company somwhere in tax paradise, summer 2014). If i asked why and how it was possible, they replied with formal letter how much sorry they are. Nothing more.

I was in touch with ViSA guys and they confirmed payment as fraud and returned my money back to me.

Around 10 years ago i was in national bank. We had small project for entrance gateway automation. Control unit was strange DIY solution.

Banks aren’t so secure as we think. At least in my country.

I worked for big oil company and even their infrastructure and solutions are far from ideal. So i don’t have false expectations about security.