I think cannabis businesses use Post Office money orders.

My clients (same ones who are going to Italy) live less than a mile from the only IRS office in Phoenix.  For exercise, they walk there to make payments and file their tax returns.  But with checks, not cash.  I pointed out that they have to go through security to get inside, but they said it's no worse than the airport.   

At least TSA has Pre-Check.  IRS should have a program like that, for custodial parents who clearly qualify for EIC and don't have a history of audit changes.  Sign up in November, then don't wait six months for your refund.