Sensors are absolutely nice to have, but depending on them is a completely different story.
I can't imagine not depending upon them, nor how to design something without a way to sense to be able to move through the world.
What viable alternative is there if not to use sensors to understand the world?
Yes I did, your comment would have been improved with specificity in the first place.
It doesn't even have to be as good as a human could be; it just has to be good enough given the problem space and the economic forces involved.
As the other comment suggested, Tesla doesn't have the greatest track record with these sensors, and putting 16.5 ton driving force behind that could have very lethal consequences.
I just wish Tesla was held to a higher standard of scrutiny.