… because they can. Don’t believe me? Read this article from the New York Times. It details how, even though they are annoyed by the fees, people are not switching banks because there is too much hassle in changing all the electronic bill paying arrangements. Banks knew this, A 2008 study showed that customers who made five or more payments online a month were 95 percent less likely “to churn,” while consumers who didn’t bank online were 43 percent more likely to leave. So why do they charge fees… because they know you won’t leave.
By the way, this is the same reason Facebook feels free to change its interface without losing customers. Once you have a large number of friends on the service, you’ll put up with the changes because your friends aren’t on the competing services. This is why G+ is having trouble taking off, and why even though periodically folks threaten to move from LiveJournal to DreamWidth, folks still stay on Livejournal or mirror their posts there… because that is where their friends are.
Businesses aren’t stupid. Greedy, yes. Stupid, no.