This is not what I stated at all: "So are you saying an contractor (or an employee before 2018) can't deduct Actual Vehicle Expenses on their tax return?"

I stated, in response to the original question, that the contractor presenting a receipt for Fuel, to be included in the payment from the customer to the contractor, is Not a Reimbursement. It's further justification that increases the total this contractor expects to be paid. It's not An Accountable Plan process, because there is no way to prove the use applies.

Also, the "gives the contractor a certain dollar amount per day" is Not Anything other than More Gross revenue to that contractor.

And then the contractor is going to report on their taxes all expenses that they have, which includes any operating cost that qualifies. And that has nothing to do with customer payments, since that is part of operations.