The IRS says on https://www.irs.gov/uac/pay-taxes-by...-or-debit-card "Fees differ from those in the table above when you choose the integrated IRS e-file and e-pay option."
They provide a link to https://www.irs.gov/uac/pay-by-debit...hen-you-e-file , which shows a different set of payment providers, with higher fees.
But when I follows those links, they show the lower fees that are summarized on https://www.irs.gov/uac/pay-taxes-by...-or-debit-card .

I have a hard time understanding what is going on. Even if the fees are higher for "integrated file/payments", why would anybody in his right mind pay the higher fee, when the same can be achieved for the lower fee when paid outside the integrated file/pay software? None of the software that I know requires payment when filing a return.

there are many factors to consider before you pay taxes with a credit card, not the least of which is the cost.The irs does not directly accept payments from credit cards, rather it authorizes several different independent companies to accept these payment on its behalf. You can find a complete list of these companies on the IRS website.Although credit card payment surcharges are illegal in some states, the federal government is itself exempt from this particular law. The companies that accept payments charge credit card fees of between 1.87% and 2.35% of the amount paid, which is added on to the charge. So a person paying a $5k tax bill will incur a minimum of $93.50 in credit card feesDespite the high cost of paying these credit card fees, there are several different scenarios in which it may be a good idea to pay your taxes with a credit card. First, there are some credit cards that offer rewards worth more than the fees. For example, there are cards that offer 2% cash back, or travel statement credits worth 2% of the amount spent. So if a taxpayer uses one of these credit cards, and avoids interest by paying his or her statement balance in full, then it is possible to enjoy the convenience of paying by credit card while coming out just slightly ahead.In addition, there are ways that credit card users might receive some interest-free financing of their tax debt. For example, almost all credit cards have a grace period that lasts between 21 and 25 days after the statement closes. So if a charge is made on April 15, and the card?s statement period closes on May 10 and has a 25 day grace period, then the payment could be due as late as June 4 and so on.

plz contact the IRS directly for sure sicne it is done by the IRS.

My question was regarding to 2 different fee schedlues and how they differ, whether payment are treaded different in any conceivable way, etc.
Whether some credit card customers can recoup some of the fees paid is irrelevant to this question.