Transactions are said to need both atomicity and consistency. But, what is the point of consistency?
Once you ensure that you either update both accounts on money transfer, you are consistent. Wikipedia article on consistency says that consistency is a set of programmatic constraints, invariants. But you are free to code your transaction operations any way. So, I feel that programmer only needs Atomicity, Isolation and Durability. Consistency is an additional convenience DB tool, like trigger or stored procedure and is not absolute low level requirement. Given AID, the programmer can always ensure the consistency. It is a simple as check user data and reject the request if some rule is broken. Right?
It looks like Wikipedia identifies Atomicity with Consistency in the Data Consistency article, but not in the article on ACID transactions.
Listening on eventual consistency, I see that developers mean that DB is always in some correct snapshot state, i.e. data are stabilized and you can query/issue your transaction upon the DB, which you could not do if DB is available in transition. That is, consistent DB is one which satisfies the constraints at any moment of time. But, it satisifies the constraints if operations are atomic. Atomicity implies that we see only transaction results, which implies that we see only snapshots, which means consistence. Why do you need to single the consistence out as if it is independent property?