You could say they already are, at least with regard to recent vehicles for the European market: https://www.powerprogress.com/news/mercedesbenz-delivers-citar

You could say they already are, at least with regard to recent vehicles for the European market: https://www.powerprogress.com/news/mercedesbenz-delivers-citaro-hybrid-buses-to-transport-firm-in-rome/8012818.article https://www.powerprogress.com/news/mercedesbenz-delivers-cit... The driver's area is entirely separated by an internal door, with an optional hole in the glass for operators which take cash. These separating doors became most widely fitted after the COVID-19 outbreak (for the drivers' safety), but they were already in use in many European cities years before that.