Why can't self driving cars be public transport? Why will there always be non self driving cars - especially 20 years out? If they're inherently riskier and cau

Why can't self driving cars be public transport? Why will there always be non self driving cars - especially 20 years out? If they're inherently riskier and cause minor irritations (slow down traffic) to major irritations (human driven cars are 6x more likely to cause a human death than a self driving car etc) then how long will we the "i'm in a hurry" allow the indulgence? And interstates are multiple lanes so 2 dedicated lanes to self driving vs 1 or 2 to human driven while we transition.