I'm not looking for startup ideas in this domain, I was just wondering "in general". If the PC + printer is already there (surely it has to be for accounting, etc.) why have a fax.
But ok, if the fax and the phone line cost next to nothing and it "just works", then sure it makes a lot of sense.
A lot of these restaurants _do_ have a PC + printer in a back room or office somewhere. If the restaurant is owned by a group (or small chain), that setup may only exist at one location.
They can (and do!) put the fax machine right by the kitchen.
But ok, if the fax and the phone line cost next to nothing and it "just works", then sure it makes a lot of sense.