Counterpoint: Amex has been issuing charge cards since the 50s, and their tech seems leagues ahead of Discover, for both charge/credit cards and checking accounts (based on my first impressions for the latter; I haven't really used their checking account as my main account).
Yes, Amex has the best app out of all banking I've used thus far. It's very fast, the UI is easy to understand, and you can do what you need to do quickly and painlessly.
The under the surface portion of the legacy system iceberg is how agile (and well-defined at interface points) backend systems are.
Most of the time, the reason a front end app can't do X is that there's no way to use/modify the internal core systems to do that.
So front end shiny is a poor litmus for how well or poorly a company's internal systems are.
Agility is probably a better proxy -- given a new business need / requirement (e.g. ACA in US health insurance), how quickly can a company execute on it?
> Agility is probably a better proxy -- given a new business need / requirement (e.g. ACA in US health insurance), how quickly can a company execute on it?
Yes, probably, but I think performance is pretty good sign too. Old legacy systems are often complex so new functionality is always bolted on-top, and not baked-in. Making architectural changes like that is risky.
And, third-party integrations are going to be preferred. So over time the application becomes incredibly slow. There's layers and layers of cruft and then calls to third parties around every corner.
