They have enough business using their existing "over the web", no need to send a truck, preliminary system design model. It's cheap and efficient and works well for many, but not the corner cases. New construction is a total corner case for them, and not worth their time.Not working with new construction and the uneconomic lease model --solar city seems to suck.
As for "uneconomic lease model"...well it works well for me, and apparently many others. Yes, one can buy for less overall cost than lease, and yet leasing is still very attractive to many for both cars and solar energy. It's far from uneconomic, it's just not maximally economic.
Like any endeavor, if one is willing to put in the time and effort, one can always find a better "deal". SolarCity's advantage is few are willing to put in that time and effort, and they are very easy to work with if you happen to fit in their box.