i think this round of delivery startups were mostly driven by concentrated capital desperate for return (plus not enough diversity of thought to recognize unconventional but interesting bets), because anyone who remembers webvan knows that the economics of last-mile logistics hasn't changed substantially with faster/ubiquitous computing and mobile.

mobile does increase availability slightly and reduces friction a little, but those weren't the core problems that needed solving to make a successful business in the space. even uber's outsourcing of capital costs wasn't a major problem that needed solving to unlock the market.

you can't beat last-mile logistics by throwing more marketing at it.