Until other public charging solutions become widespread, the Supercharger network will continue to be a killer feature for Tesla.
We have some spaces with Chargepoint chargers where I work, and they are powered by several electrical boxes that are each about half as big as a parking space. There is some serious juice being pushed through those -- and the Chargepoint chargers are only serving 30-40 amps, which is about the same as a home charger and nowhere near what a Telsa Supercharger delivers.
This kind of stuff is not trivial, or cheap. Tesla spent a lot of money to get their network to where it is.