Databases for banks (and I presume travel agencies as well) were made in the 1980s and haven't been updated since
Well, that's a gross over-simplification.... but...
We might do when there's a good reason, like maybe when decentralised clearing becomes a thing with block-chain
Hell NO. The last thing anyone needs is programmer-lawyers or lawyer programmers. Someone needs to come up with a killer reason for the cool idea which is blockchain, but I haven't seen it yet
but a little bit of values dissonance isn't really a good enough reason to undertake a multi billion pound overhaul.
Yes, yes it is. When I worked for an investment bank, I got talking to another person who told me that Barclays Capital did an audit and discovered that in the region they'd looked at, they had more servers than employees, and they didn't know what most of them were even doing.
The software development was so chaotic, that at least 3 teams were doing the same project mine was, and they'd already tried this project at least once before.
I had to leave and go back to my original industry I was so appalled.
Changing how a default is determined is miniscule in the grand scheme of things, and if you can't figure out how to change it, then I have bugger all confidence in you holding my money (honestly, I have experience of many industries - your money, in my experience is more competently handled by an online betting firm than a bank!)