>In the US, Online purchases with a debit card generally do not use the lower fee debit card networks, but instead use the credit card networks. Basically every debit card in the US is co-branded by one of the credit card companies, and can be processed by merchants as if it were a credit card.
Yeah. So what?
It doesn't make any immediate, practical difference to me.
Sure, it would be great if fees were lower. That would (presumably) reduce price increases over the long term and allow merchants to increase their gross profits. Having high "processing" fees is rent seeking at best and is likely a drag on the economy.
That said, GP's comment[0] (which is what my comment was addressing) that "The thing about debit cards though...they don't work for online payments which makes them effectively useless." is (at least in the US) flat wrong.
Edit: Removed extraneous editorializing.
[0] https://news.ycombinator.com/item?id=32503287