Same-day-delivery is kinda solved in other countries - read more on stories of Meituan[1] or JD.com[2]. Granted, the labor cost, infrastructure are different. But answer is probably not gig-economy delivery but self-serve lockboxes, robots or drones. By the way, delivery workforce use electric mopeds, not diesel vans like we do here in America.

[1] https://www.scmp.com/tech/apps-social/article/3025295/meitua...

[2]: https://www.prnewswire.com/news-releases/jdcom-speeds-packag...