As a retailer (NOT a restaurant) taking cards has its downside, but we do it because there is a net benefit. Primarily, it's a convenience to many customers and sometimes leads to higher sales. A secondary benefit is not having to schlep to the bank as often to make a deposit.
Obviously businesses factor the (not trivial) cost of handling cards into pricing.
As noted in earlier posts, there are charges per transaction, charges for a % of the transaction amount (including sales tax) and a bewildering variety of added fees which are always going up. Fortunately, my business' price points are sufficient to cover the costs. I would guess that for a small retailer the total will be at least 3% of sales. For businesses on a tight margin, that is significant. Some retailers such as grocery stores have a net after taxes of 2% of sales or less.
On the downside, there is the irritation factor of dealing with credit card companies. As Cathy2 pointed out they are your unwanted partners. I liken them to Big Al's goons, except instead of coming round once week to collect several C-notes, they are looking over your shoulder with every transaction.
Similarly, negotiating terms is difficult for small businesses. We don't have the volume that a McDonald's does to work out a low per transaction fee. Even the big guys have a tough time of it. Several years ago Wal-Mart and Target were plaintiffs in a complicated law suit against the banks over credit card practices. It became a class action and I was happy to let them take the lead.
Even so it took years to settle. I think my share of the settlement was about $50. Whoopee.
The card statements are masterpieces of obfuscation with a bewildering variety of fees and rates. I was trained as a CPA, but have rarely been able to trace the actual cost for a particular transaction. All I really know is the total amount it costs me each month.
Finally, people love to get travel miles or other benefits when using their cards. I hope you don't think that it costs the banks anything to offer these goodies. In fact, I think it's a profit center for the banks.
The money to pay for your airline points come out of the retailer's hide. The trasnaction rates for any particular card vary depending on how much the banks charge for a level of benefits.
A retailer's agreement (typically locked in for 3 years by the way) may have a base rate of 1.9%, but that's only the base. There are surcharges for many cards and there is no way of knowing beforehand what that charge will be. It could be an extra 1% or even more.
That's the story from the inside looking out.
Where there’s smoke, there may be salmon.