Your link only pertains to one way the IRS takes cash payments. They also take cash payments at Taxpayer Assistance Centers (TACs). You don't have to pay cash at a private corporation, you can go into an IRS office and pay cash.

https://www.irs.gov/payments/pay-your-taxes-with-cash

https://www.irs.gov/payments/what-to-expect-when-you-pay-cas...