I have read that in my country, one of the reasons why metro systems (and perhaps bus too), which for now are state-owned, are not more automated/driverless, is

I have read that in my country, one of the reasons why metro systems (and perhaps bus too), which for now are state-owned, are not more automated/driverless, is workers' union pressure for it not to happen. In fact one line was fully automated (but still had conductors just to open and close doors) but the system was scrapped some years ago; the official reason was that the system was obsolete, but many people think that additionally, there was some lobbying for automation to be removed instead of modernized (which would have been more economical in the longer term). What I mean is that there are more than technical and legal challenges to self-driving transportation systems, especially when those systems currently employ human drivers who are obviously not willing to lose their jobs.