[riffraff]

What do you think happens to the cash at the end of the day?

Managing cash has costs too, they're just harder to quantify: you have to ferry it to a bank, you have increased risk of theft, fraud, and robberies, you need extra time to actually check the register etc.

And then you risk losing business if you don't offer card payments because it's just more convenient for most customers (you may like wise lose some if you don't take cash, but that's a vanishing market).

[lxgr]

One big difference is that there's competition between cash handling providers, while there's essentially zero wiggle room for interchange fees.

That's what makes interchange and network fees so much more problematic than acquiring fees. There's very healthy competition between credit card acquirers and payment service providers on both features and price, but in the end, you have to accept whatever card your customer has or there won't be a transaction.

[renhanxue]

In the EU the authorities have recognized the power of the card networks and introduced price controls on interchange fees in 2015, capping them at 0.2% for debit cards and 0.3% for credit cards.