The last available seat

Original non-fiction-style practice text.

At the ferry office, the last seat on the afternoon crossing appeared to be empty. A traveller pointed to it on the seating plan and offered to pay immediately. The clerk, Inez, explained that it had already been allocated, although no name was printed beside it. The traveller thought she was refusing a straightforward sale.

The seat belonged to an escort who would join at the island landing. His passenger was already on board and needed assistance for the final part of the journey. The escort’s own name would not be confirmed until his employer finished arranging the shift. The booking therefore showed a role rather than a person. Selling the space now could leave the passenger without the help promised for her arrival.

Inez invited the traveller to wait until the reservation deadline. If the escort cancelled, she could release the seat. He looked again at the plan, which recorded occupied spaces in red and available ones in white. This particular square was white, but a small symbol beside it linked to a note on a separate screen. Inez asked her manager to change that display before the next sailing. She was tired of having to explain an arrangement which the diagram seemed to deny.

Give two reasons why Inez cannot immediately sell the apparently empty seat.