Yes but the "Don't copy that floppy" adage is definitely an American thing. So is CFAA, which makes it easier to have prosecuted Aleynikov under CFAA instead of some other laws. It worked for Swartz.
Taking the source code driving a 9-figure financial services practice at one of the world's largest investment banks, one that happens to pay you a salary that is notably generous even for tech, and relaying it to your new employer, a competitive firm that happens to have just 3x'd your salary, is simply not analogous to "don't copy that floppy".
This wasn't King's Quest.