> Surely if it's Tesla making the decisions, they need the insurance?

Why surely? Turning on cruise control doesn't absolve motorists of their insurance requirement.

And the premise is false. While Tesla does "not maintain as much insurance coverage as many other companies do," there are "policies that [they] do have" [1]. (What it insures is a separate question.)

[1] https://www.sec.gov/ix?doc=/Archives/edgar/data/0001318605/0...