The transformer here will be dedicated solely for the superchargers: no sharing here. There’s a couple out there where the business attached will share the transformer but it’s likely because the business and the superchargers were planned and built simultaneously: Modesto - Joyce Ave, Ripon, etc.
For this location there was a change recently on the concrete pad location which is responsible for at least part of the delay. I’m unsure what permitting process has to occur if you change the construction layout well in to the building phase.
On a related note, large transformer backlog is definitely getting better but the big utilities are not fully recovered yet.