Correct, part of safer street and road design is supporting transit, biking, and walking.

That said, it's essentially impossible to get rid of cars entirely, and you can see that just by looking at countries or even regions that have good transit and notice that they still have tons of cars. Even Singapore has lots of cars, and the entire country is a super-dense city-state!

So it's definitely worthwhile to develop self-driving cars and trucks, even if you have fantastic transit and biking and walking available.