The problem is that the industry standard of banking is eventually consistent. Whilst having atomic transactions is necessary, it's not sufficient: Using banks

The problem is that the industry standard of banking is eventually consistent. Whilst having atomic transactions is necessary, it's not sufficient: Using banks as a teaching metaphor for RDBMS systems is like using animals as a teaching metaphor for polymorphism. From a naive point of view it works, but it does more harm than good because students walk away thinking that they have a solution to a problem that isn't actually sufficient for it.