Source: https://www.clarifai.com/
> In order to connect brands with the images they’re looking for, Foap uses Clarifai to consistently tag all these photos to make them easily searchable.
Pricing: https://www.clarifai.com/pricing
More on Foap <-> Clarifai: http://blog.clarifai.com/uncover-buried-stock-photography-tr...
This are the results: NONE of them identified people as mariachis ;-)
Microsoft: Captions: "a group of people on a boat" Tags: outdoor, sky, tree, boat
Clarifai (TAGS): people, vehicle, water, festival watercraft, transportation system, tourist, travel tourism, city, adult, group boat, recreation, man, outdoors competition, canal, sfw transportation, travel
Google (tags): Boat 79% Vehicle 77% Boating 67% Waterway 58% Raft 53%
My only conclusion is that both Google, Clarifai, and Microsoft are doing a great job. You should take a look at what you need and choose the best provider.