The program was apparently put in place following another one of the company's schemes, in which it attempted to undermine its main rival by creating fake Lyft accounts and tricking drivers into thinking there were riders in various locations around the city, enabling Uber to see the eight closest Lyft drivers to each fake rider. Once it realized Lyft assigned a numerical code for each of its drivers, Uber figured it could easily track them over a longer term to determine which drivers were also driving for Uber. This allowed them to target specific drivers and incentivize them to ditch Lyft by offering bonuses, which the company was evidently paying out in the range of tens of millions of dollars per week.
According to The Information, only a select few at the company knew about the program (including founder and CEO Travis Kalanick) and it was only used for about two years, ending in 2016. Lawyers who have represented Uber previously claim the company might face legal trouble over its use of Hell, including breach of contract, unfair business practices, stealing trade secrets, and possibly violating the Computer Fraud and Abuse Act.