Peer to Peer delivery services
These companies are new companies that rely heavily on tech and a freelance workforce. Unlike the professional courier services the owners have probably never delivered a package professionally, and the couriers probably never built an app (so there is a disconnect there). But as far as the consumer is concerned this is the best choice for impulse buys. No you may never get to know the owner or even your courier for that matter, but oh-boy do they get your burritos to you quick-fast!
No better option for food deliveries. Couriers are usually extra friendly (Their ratings and tips depend on it), the orders are easy to book, easy to track, and relatively inexpensive (Under $5 in most cases), and are available in just about every city.
The cons are that outside of delivering food or groceries they are not very reliable. you might want to think twice before using a peer-to-peer courier like Task Rabbit or Uber in a commercial district during business hours. The parking fees, security protocols, driving restrictions, and aggressive driving from professional couriers might be enough to send your peer back to the outer-boroughs.