I believe Jim in Houston meant support in terms of electrical capacity. Some distribution circuits (especially in rural areas) are still 4160Y2400V from the substation to the proposed supercharger location. An eight stall V3 supercharger needs 500KVA which is about 25% of the total capacity of such a circuit. If the circuit is near capacity (and most 4160Y2400V circuits are at or near capacity) then adding a new 500KVA service requires increasing the voltage of the circuit (typically to 12,470Y7200V) which involves replacing the transformer (often a pair of transformers) in the substation and every pole top and pad mount transformer between the substation and the proposed supercharger location, then installing a set of step down transformers immediately after the supercharger to avoid replacing the pole top and pad mount transformers along the rest of the distribution circuit. That’s a huge job and most utilities would try to make Tesla pay for it. In some cases it might be possible to instead re-conductor the circuit with larger conductors from the substation to the supercharger location, but most 4160Y2400V circuits already have the largest practical conductors from the substation to the first large customers, so it’s either raise the voltage or install a whole new distribution circuit from the substation. In some cases the substation doesn’t have space to install larger transformers. These sorts of distribution circuit upgrades could easily cost a lot more than a supercharger. Another option would be for Tesla to install a huge solar canopy and a few megapacks, but that would be even more expensive.
It’s not rare for 12,470Y7200V distribution circuits to be at or near capacity. They can be upgraded to voltages as high as 34,500Y19,920V, but most utilities don’t use distribution voltages that high.
I’m confident that many proposed supercharger locations have been rejected because the electrical capacity wasn’t available (without expensive upgrades). BTW, Tesla has the same issue siting service centers, which usually require 750KVA or more, compared to traditional stealerships which are often 100KVA or 150KVA.