General Motors said Tuesday it will no longer fund the development of a commercial robotaxi business and will instead absorb its self-driving car subsidiary Cruise and combine it with the automaker’s own efforts to develop driver assistance features — and eventually fully autonomous personal vehicles.

In light of such difficult economics, what made robotaxi the dominant go-to-market strategy for autonomous vehicles? To understand the reasons why, let’s consider the history of AVs. The idea of autonomous vehicles has been around for decades.