Doesn't that kind of software have annoying dialog boxes saying "Are you sure you want cause financial meltdown?"? Or at least a less intrusive "Did you mean 'm'?"?
I think the first one is actually the better choice.
It's really surprising, assuming this is really the cause, that a single letter typo could have such an effect and this has 1) never happened before and 2) not been caught in testing.
I doubt it's a person that made money. Usually individual investors lose big time when stop loss orders are activated, it's the institutional investors that win.
I have actually worked on such software. When a price comes in - a quote - you have a fixed amount of time to respond before it goes stale, usually a few seconds. It's assumed you know what you're doing and that you want to move quickly. Same as operating any other high-powered machinery.
I remember a feature request from a client of ours, we had keyboard shortcuts of k for thousand, m for million and b for billion. They wanted t as well.
It probably should.