No treatment of automotive invention can be complete without a discussion of driverless cars. When it comes to autonomous vehicles, it’s easy to be optimistic—and pessimistic—about it happening soon.

You could spend weeks online reading the latest cheerleading and doomsaying about AVs and come away more confused than ever. Join the club.

So we’ll stick to a few facts regarding why this might happen soon, and why it might not. But it seems there are more reasons to think the mainstream use of driverless cars is still decades away than reasons to think it will happen within a few years.

  • SOONER: Because about 94 percent of vehicle crashes are caused by driver error, there is reason to get the technology on the road as soon as possible in order to save an estimated tens of thousands of lives each year.
  • LATER: General Motors’ rollout for its self-driving car division, Cruise Automation, is years behind schedule. Theweek.com reported in November that “prototypes by Ford, Tesla, and the Google affiliate Waymo would still flunk driver’s ed.”
  • SOONER: Early this year, Britain’s government said driverless cars will be on the country’s roads by 2021.
  • LATER: In March 2018, an Uber-owned AV going 40 mph in Tempe, Arizona, fatally struck a 49-year-old pedestrian crossing the street in the dark when the vehicle’s perception system got confused by the bicycle she was wheeling. Uber suspended testing nationwide. Per Theweek.com, “AVs sometimes react to parked cars as if they’re moving, and they get overwhelmed passing through construction zones. They’re shaky at challenging maneuvers like turning left against oncoming traffic.”
  • SOONER: An article in Forbes magazine two years ago predicted that there will be 10 million self-driving cars on the road by 2020, with one in four cars self-driving by 2030. (The key words above are “two years ago.”)
  • LATER: Heavy snow, rain, fog and sandstorms can obstruct the view of cameras. Light beams sent out by laser sensors can bounce off snowflakes and not recognize them as obstacles—all while many companies are still trying to master the difficult task of driving on a clear day with steady traction. Roadway and lane lines aren’t standardized around the world, so vehicles have to learn how to drive differently in each city.
  • SOONER: Driverless vehicles are a common occurrence in Las Vegas—which last year had the 25,000th passenger trip provided by a collaboration between Aptiv and Lyft. The system uses several autonomous vehicles to ferry riders around the city.
  • LATER: Public infrastructure such as stoplights, street signs and buildings will need to be equipped with advanced sensors to help driverless cars interact with their environment. This will require close collaboration between automotive companies and government agencies, which is potentially rife with problems. State and national safety regulations will have to be changed. And how long will it take for agreement on revamped insurance regulations?