> This is only true if you think of them like a bank account. Every credit card statement I've ever receive has shown the amount I owe as a positive amount.

I just checked my online banking - I bank with Nationwide, a UK building society (a bit like a US credit union but functions like a bank). In the main statement of accounts, which looks like this [1], the credit card balance is shown negative. So is my mortgage, which makes for a depressing overall sum! I won't bore you with more detail but generally they mostly stick to this pattern in other screens. Oddly, in that example screenshot, the credit card balance is shown as positive - I'm not sure if that's because it's just an example and they faked it wrongly or because the way balances are shown have changed since that picture was taken.

I've never had a credit card with anyone else, so that's why I'm surprised that the debt is presented as a positive number. It's interesting to see (from your comment and others) that's it's normally done that way. My initial cynical reaction was that this is a marketing ploy to make you feel a bit less bad about it, and I'm not surprised that Nationwide doesn't follow suit given that it's not run for profit.

[1] https://i0.wp.com/money-watch.co.uk/wp-content/uploads/2011/...

> The "credit card" account is a liability account

Interesting, thank you, I hadn't heard of "liability account" before. So it seems that it is something accountants really do use, not just the cynical marketing plot I initially thought. But it still does seem an unnecessary complication to me compared to just having all accounts working the same way (but some happen to be negative). Maybe it's a just mathematician / computer scientist thing of preferring things that make mathematical sense rather normal intuitive sense, a bit like zero-based indexing or end iterators that point one past the end.