I said basically this in another thread, but nobody wants to debate, so here goes again.
I think Tesla is doing the right thing.
It should probably fall to each EV manufacturer to make sure there is charging infrastructure to support their customers.
By the end of 2013 Tesla will probably have at least 5000 customers in California between SF and LA.
One supercharger supports about a dozen cars per day without obnoxious scheduling and long wait times.
To support 1% of those 5000 cars wanting to make that drive on any given day they need 4 superchargers.
To support 10% of those they need 42 of them.
The average case is not important, only the worst case, like a big holiday weekend.
Why spend that money to support other manufacturers EVs?
By the end of 2013 there could easily be 50,000 other EVs along that corridor, most of them won't be capable of such a long highway trip, but if they try at 1/10th the rate of Teslas, they block Teslas from the resource.