Earlier quoted context omitted.
Yes, there are probably very few outlets where mail trucks currently park. These things are parked in the middle of parking lots, not in garages. And you need more than one outlet, you need one for every truck that parks there. And I am sure no current USPS office has power service hooked up for several hundred amps of draw that was never anticipated to be used. There's no way to do a project this big without phasing…
These vehicles ARE being phased in slowly. And installing 100-200 Amps of commercial service is cheap, and I actually think would largely be unnecessary as they can be set to charge at night when office demand is super low.
And yes, installing service is "cheap" but it takes time.