If the end buyer's money is already in escrow, why pay a funder?

Using C's money to fund the A-B leg is what people call a pass-through or dry close, and whether it happens comes down to two documents rather than to arithmetic. First, the title or escrow company's own policy. Plenty of them won't disburse one buyer's funds to acquire title for someone else's purchase, and some states have escrow rules and funding-timing requirements that make it a non-starter, so this genuinely differs state to state and even company to company in the same city. Second, and this is the one people skip, the C buyer's lender writes closing instructions. Those instructions routinely say their loan proceeds may only fund their borrower's purchase from a seller who already holds title. Read that page and the question answers itself for that file.

So the funder is there because the escrow officer says no, or because C's lender says no. If both say yes and it's a cash C buyer, wholesalers do skip the fee. Ask the specific title company what they'll do before you assume either version.