Yup. Further complicating things, ACH isn't truly settled for a 6 months! ACH's can be charged back for 180 days and there is no adjudication process, like with credit cards. If an ACH gets charged back, you lose the money, that's it.

The other major complication with ACH is that most Americans use credit cards for the credit (70% hold a balance). That is something that won't be solved. Others like the benefit of rewards (miles, dollars, whatever). To get payers on board, you need credit, rewards, and exclusivity (i.e. is this the only payment method available at somewhere where I want to shop). The last 2 meaningful companies were paypal and discover card. PayPal had millions of Ebay sellers using PayPal AND they initially paid people to become members. Discover card started the cashback movement and was the only electronic payment option at Sears (largest retailer in the world at the time).

More details and discussion in a previous article: http://news.ycombinator.com/item?id=3238880

ACH's are essentially free - there are some costs but Dwolla is part-owned by a credit union which probably helps lower the costs. They have major fraud-related costs, but given that fraud under $10 should be very small, their costs aren't much