We all know that there is a lot of data being pushed in banks networks, but your ATM example may not be a very good one. The transactions you are talking about do not occur in a single bank.
Twitter in not only big in terms of traffic. 200 million tweets per day is not small, even if a tweet involves less processing than an ATM transaction.
You can also consider Facebook as an example of website dealing with big data.
Twitter in not only big in terms of traffic. 200 million tweets per day is not small, even if a tweet involves less processing than an ATM transaction. You can also consider Facebook as an example of website dealing with big data.