Expense policies defined per category, claims raised by the people who actually spent the money, an approval that posts the entries, and reimbursement recorded against the claim it settles.
Not a receipts folder. A claim here carries the policy it was measured against and the approval that let it through.
Both exist because both happen, and neither should mean editing history.
By the time a claim is approved, the accounting is done. Reimbursement is the only thing left.