The limits apply only to debit card, credit card or cash payments.  If a bank is going to give you 100,000 miles after you spend $8,000 on a new card in three months, you're going to be looking at ways to do it.  And charging your taxes is a recommended method, even if the fee is close to 2%. $150 for a round trip business class lie-flat seat to Europe?  I'll take it.  IRS must be paying something for the privilege of accepting such payments, if they want to limit their use.  

As for cash payments -- that costs $4 if you want to do it at the corner convenience store, but the fee must not cover the entire cost.  And the limit is $1,000 per day.  https://www.irs.gov/pub/irs-pdf/p5250.pdf