For car dealers and manufacturers, the math is more complicated than that--the lease can be a loss leader, which may be useful to the dealer or manufacturer for any number of reasons.

In the early 2000s it was not unusual for leases on slow-selling models to have negative interest rates (and that's with a realistic residual), not sure if that is still the case today. I certainly don't ever remember seeing a negative interest rate on non-lease financing offers, not sure why.