The real insight will come when you realize every very large scale financial institution you do business with will retain your money without hesitation or remorse if they feel they have the legal right to do it.
If there was a mistake in the transfer and the money wouldn't belong to me, even if legal, I would return it. I'm sure many would do the same. Not everything that is legal, is moral.
We would likely be guided by a sense of personal ethics and our own values, which would make us consider returning money even if through a technicality we had the legal right to keep it.
At the level these companies are interacting at, there's no such thing as ethics of this kind. The legal system is the values system, and if they can make money on a legal technicality they'll do it without further thought.
They're more like great vampire squids wrapped around the face of humanity, relentlessly jamming their blood funnels into anything that smells like money, as someone more eloquent than me once noted.
Worth remembering if you find yourself dealing with large scale financial institutions.
