Credit cards aren't an apples-to-apples comparison because of the risk to banks of default. An apples to apples comparison is ACH, which is free, and now same-day service is available.
No, it does not depend on which card you're using. Everything costs a few percentage points more because of fees for the merchant. You pay this no matter what card you're using. They don't offer you a different price for using a specific card, though a handful do for using cash (gasoline comes to mind).
Sure, but merchants can generally get fees that are only slightly higher than what you get in cash back. Square charges a 2.75% fee (and some of that goes to Square, presumably), and there are 2% cash back cards with no annual fee easily available (I use the Citi Double Cash one). So even if your store is raising prices by 2.75%, you're effective price only goes up by about .7%.
If you want to get upset, get upset at how if you have poor credit, you're not eligible for these cards, so really this is credit card companies stealing from poor people.
So what you're saying is I'm getting 0% cash back and paying .7% more for everything. Still doesn't sound like a win to me, and it still doesn't matter what card you get because no card is giving you more back than they're making off your use of it. That's not how money works.
You're paying 0.7% primarily for the ability to pay, and also for the ability to pay on credit, to get a chargeback if needed, to cover fraudulent use of your physical payment device including loss, etc.
This is a) a good deal on its own and b) a much better deal than Bitcoin, which provides only the first of those things, and only reaches 0.7% if your transaction is over about 3000 USD.
If you think this is a bad deal, I'm curious what you think is a better deal and who's offering it.
A better deal is a debit card (somewhat fewer protections but saves people probably a 1% fee on average) but unfortunately the banks have set it up as a tragedy of the commons where it makes sense for me to get my 1-2% cashback since the 2.7% credit card fee is already built into the price due to other people.
With regards to Bitcoin though, I agree you need a much lower fee coin to make it feasible. The lightning network brings the transaction fees on Bitcoin to zero though from what I understand so maybe thats the answer.
Now try sending some of that money to a third world country and see how much they get between the fees they pay western union and the thugs waiting outside to 'tax' you.
From sale to end point .. where'd my money go ? lol