Just as the most important context for an Amazon review might not be the online storefront, where a customer sees it, the most important context for that Seamless star average might not be a Google result, or even how it appears in the Seamless app. The real context is how the Seamless algorithm interprets stars and uses them to determine whether to show a prospective meal-orderer one establishment over another.

The Uber Trial

Nowhere is this mutated, empowered role of the star rating clearer than in the gig economy. “Star ratings are an enforcement tool that Uber has for how users should behave on the job,” said Alex Rosenblat, a researcher at Data & Society and the author of “Uberland.” Star ratings are integral to Uber’s operation, but how they appear is subtly and significantly calculated. Riders will see their driver’s star rating before they get in the car, but only after the driver has been assigned to them; there is no actionable comparison, or reading of reviews, or customer evaluation. That’s taken care of by Uber’s own software, behind the scenes. (Drivers can see riders’ ratings before they choose to accept jobs. However, turning down too many jobs can affect their status in the app as well, although not in the form of star ratings.)

Uber drivers are contractors, not full-time employees. This is both integral to Uber’s business model and, in different markets and courtrooms around the world, currently in dispute. In the meantime star ratings provide a conduit through which Uber can assertively command and micromanage its “partners.”

Drivers receive communications from Uber not about what Uber wants them to do, exactly, but about what five-star drivers do. Rather than telling its drivers to open doors, or not to solicit cash tips, or to stock water bottles in their cars, or not to ask for a five-star review, Uber can tell its drivers that users have shared that they prefer some behaviors, and dislike others, and that acting on these observations is a way to optimize their own ratings. The possible upside is limited to remaining on the app, and perhaps being privy to certain driver promotions.

In addition to the quality of the ride, and, say, the riders’ moods, or feelings about Uber in general, a crude star rating system might serve as a “facially neutral route” for discrimination to manifest in the platform, and to eventually “creep in” to employment decisions, according to a paper to which Ms. Rosenblat contributed.

Contrary to the star rating as a symbol of the wisdom of the crowd, or the circumvention of critical gatekeepers, Uber’s system seems mostly to empower Uber, as a marketing tool and as a system of control. How else to explain a five-star scale whereby customers never see a rating lower than a 4, while many working drivers live in a state of constant anxiety about how they will be reviewed?