1 - the cars do not need road sensors to operate. Companies like Here are building a massive database with very precise road data collected by many thousands of cars that (in some cases unknown to their drivers) are recording road details down to a matter of inches. Tesla cars already have data that modifies speeds of cares in cruise control to adjust for upcoming tight curves etc. Not yet perfect but the data is accumulating very fast.
2 - the sensors and cameras that you are referring to are used to divert cars (whether autonomous or human-driven) along the quickest route based on real time traffic flow. We already have that technology in use and much of that infrastructure is privately built.
A third point (from the article, not your post) - the Tesla that crashed was not an autonomous car, the setting in use was intended to be supplemented by human observation and reaction. The driver failed, not the system.