A key selling point of rideshare services like Uber and Lyft is their transparency. Users know where their ride is, how soon it will arrive to pick them up, and how much the fare will be to their destination.

The next level of transparency would be the ability to easily compare time-to-pick-up and ride fares among the competing rideshare services, much the way consumers can use online travel agencies to compare prices of tickets available for travel on different airlines.

In fact, there are several such cost-comparison apps available for rideshare customers. Zailoo, for example, from Delta Prairies, LLC, boasts the following features:

• Compares fare estimates between Uber, Lyft, Taxi, Flywheel, and others
• Compares ETA (driver time to rider) when available
• Displays distance between pickup and drop-off, estimated travel time

Having reviewed their options, users click to open the app of the chosen service and book their ride. That’s transparency!

But the future of such comparison apps is anything but assured. A newly launched Uber-Lyft comparison service, urbanhail, has been warned by Uber that displaying its ride costs violates Uber’s policy regarding acceptable use of its data.

According to the Boston Globe, Uber advised urbanhail’s developers, a group of Harvard business students, that other companies are explicitly forbidden from using Uber’s data “in any manner that is competitive to Uber.” Given Uber’s well established willingness to take legal action to further its business agenda, that threat has to be taken seriously.

(Frequent travelers will be reminded of the skirmishes between airline loyalty programs and companies that marketed so-called mileage managers, apps that used screen-scraping technology to consolidate users’ account information in a single view. The difference, of course, is that users didn’t use mileage managers to make purchase decisions, as they most certainly would with the rideshare-comparison apps.)

Whether rideshare companies can legally prohibit third-party apps from obtaining and displaying their fares and other particulars remains to be seen. It will probably take a court case to establish a binding precedent.

Stay tuned.

Reader Reality Check

Should Uber or other rideshare services be allowed to withhold their data from comparison apps?

After 20 years working in the travel industry, and almost that long writing about it, Tim Winship knows a thing or two about travel. Follow him on Twitter @twinship.

This article first appeared on SmarterTravel.com, where Tim is Editor-at-Large.