By that rationale, no-one would by the more expensive fully-comprehensive insurance (where your own car is insured, not just third parties) but they do.
And that makes sense, you can just return the car and get a new one. And lease contracts fees reflect this. If you have a fixed term lease, then returning a car ahead of time costs you, so you opt to repair it, and probably the leasing company wants it repaired at a brand licensed garage, so higher prices on that means you're likely to get a proper insurance, but you get the lease for cheaper.
By that rationale, no-one would by the more expensive fully-comprehensive insurance (where your own car is insured, not just third parties) but they do.