Yea, but those are different services that utilize the history of your transactions. What reason does an online retailer have to access that level of detail? Shouldn't they simply be able to accept the information on the credit card for the sale?

They can reduce their risk by doing this. For online retailer there is always risks in accepting card payments. (Not saying this is a good idea, just trying to find reasons).

Whose risk is reduced? The retailer or the bank? Certainly not the cardholder.

The retailer and only the retailer.

It probably reduces fraud chargebacks to nearly 0.

True, but they have a legitimate need to access your banking info: they need access to your transaction history to function. The absurdity here is asking for bank login info just to make a purchase.

Sites like Mint do this to retrieve your banking history. Asking for banking login details seems to be the standard way of doing that sort of thing. (Don't get me wrong, it's still terrible, but it's not like the banks provide an API you can log in to with oAuth or something.)

This is different; mwave is a retailer, all they're doing is receiving a payment.

I don't think there is reason to any longer. Most banks now have a trust relationship with feed providers like Yodlee etc. We use Xero, and I believe they use Yodlee to pull bank and credit card transactions in. IIRC we had to authorise the transfer with Yodlee, and not with Xero directly (i.e. Xero doesn't get to see or capture our bank login details).