[potatolicious]

Humans are really, really expensive. Even working at minimum wage, the amount of time it takes to get from point A to B in most cities is large enough that the effective human cost (not to mention fuel, insurance, etc) can easily go above $5. Are most people inclined to pay a $5 surcharge on a $10 fast food meal?

Not to mention the costs go up if you demand prompt service, since there needs to be more slack in capacity.

In certain places like NYC they skirt around this by not having on-staff delivery people, and simply contracting the deliveries out piecemeal, on-demand... The trick to supporting this is, of course, lax labor laws (I wouldn't be surprised if most of the delivery people aren't making minimum wage), and an enormous concentration of restaurants to justify the supply of an independent delivery force. This is unrealistic in a lot of jurisdictions.