Large cities are designed to get people outside, not keep them inside. A delivery raiload would take up space that could otherwise be used to transport people.
A lot of transportation is required into cities to deliver food and supplies into supermarkets and then homes. If you improved that you'd have more space and time for fun
Objection: most large cities haven't been designed. They grew, usually starting because they had a significant transportation advantage (seaport, seaport + river, river junction, river + pass).
