Back in the 70s, PRT considered the future of transit: driverless trams easier than driverless cars
CabinTaxi system slated for Detroit and Hamburg
Technology rolled into Raytheon 1996-1999, later disassociated into Taxi2000 SkyWeb Express
Boeing also working on people movers, deployed only operational system in 1975; software and maintenance handed over to local staff in 2003
ULTra system in UK winning near-term contracts for parking-lot people movers
Major failing in economics: very expensive infrastructure per mile; cannot compete on medium density suburban landscape designed for cars