> DoorDash adds value by delivering more efficiently than small businesses can on their own...DoorDash is competing on one main dimension: cost. And how do they achieve lower cost than a mom & pop macaroon shop? By scaling. Operating at scale is their main competitive advantage.

You make some good general points in your comment, but since you're holding up DoorDash as an example of success, I thought I'd point out that DoorDash is just one of a number of "on demand" companies that are currently en vogue.

In many cases, their ability to scale is heavily dependent on their ability to shift major costs (taxes, vehicle operation, commercial auto insurance, etc.) onto their workers, who they classify as independent contractors. The big question is whether the workers are actually independent contractors. This is a topic of discussion in legal circles[1] and the trend does not look favorable for many of these companies[2]. Uber is already being sued for misclassification[3] and the same attorney says she's looking at Homejoy[4].

One adverse outcome in a legal action could change the economics of these businesses significantly, and potentially even put some of them out of business.

[1] http://www.pepperlaw.com/publications_article.aspx?ArticleKe...

[2] http://www.msnbc.com/msnbc/fedex-loses-court-case-against-dr...

[3] http://uberlawsuit.com/

[4] http://www.washingtonpost.com/news/storyline/wp/2014/09/10/a...