The fear inherent in giving to any charity is that they'll just line their pockets with your money rather than giving to those in need. This fear cripples organizations, limiting their ability to hire the best people and spend money on infrastructure to increase their impact.
Humans of New York sidesteps this problem by separating the business and the charity.
The drip, drip, drip of honest, real, and intimate stories creates a strong emotional connection for readers. This emotional connection is leveraged in two ways. First, to sell books which provide a source of "normal" income. And second, to encourage donations for specific causes, like pediatric cancer, inmates, and refugees.
The vast majority of the money gathered for these causes can go directly to the causes, because Brandon has other sources of income for keeping the website up and his family fed.
This is a model I hope others will follow.