It's not hard to do. Google has been able to do it for some years. It's difficult to build a service around cars that are only autonomous on the highway, so the

It's not hard to do. Google has been able to do it for some years. It's difficult to build a service around cars that are only autonomous on the highway, so the autonomy companies pivoted to in-city driving as a natural next step toward having no safety driver. [edit: it's hard to do, but has been done a couple times over by a couple of companies]