Ask any independent hotelier with a restaurant where they lose money and they will not say food cost. They will say charges that never made it to the room.
The mechanism is always the same. The till and the front desk are separate systems, so "charge it to the room" means a docket, a name, a room number and a promise to key it in later. Later is a busy service. The docket is spiked, or lost, or keyed against room 12 when the guest was in 21.
The scale surprises people. A property doing forty covers a night with a fifth going to rooms is handling roughly 3,000 room charges a year by hand. A one percent loss rate is thirty missed bills; a five percent rate — which is realistic on a busy Saturday — is a hundred and fifty.
When both sides share a billing anchor, there is no docket. The outlet bill is settled by a cash-equivalent tender and one aggregated line lands on the stay folio, correctly taxed at the outlet so the guest is never taxed twice. And the reverse guard matters as much: checkout can refuse to complete while an outlet bill against that room is still open, and name it.
Why this matters to you: this leak is invisible by construction — you cannot report on a charge that was never recorded. It does not appear as a variance, it appears as a food cost percentage that is mysteriously worse than your recipes say it should be.