How does public transportation work in areas with population density too low to fill a regularly scheduled sedan, let alone a bus?
How does public transportation work when it takes 2-3 times as long to use public transportation than to drive your own vehicle?
How does public transportation work when you need to bring large items home from the store?
How does public transportation work when you want to hiking in a national park?
There are a lot of situations where public transportation works well, but a lot of places where it doesn't work for any realistic amount of money you put into it.
There are also driving conditions that self-driving cars will not be able to figure out.
And Tesla is kinda asking for problems calling their driver assist package 'Autopilot'.