It's interesting how this sounds like a cutting edge experiment, while this is a common thing to see in Germany and other European states for quite a while now.
The fact that putting EV chargers in lampposts works in Europe doesn't necessitate that doing so will work in the natural environment, built environment and cultural context of the US. They have to do their own assessments to work out the best solution to the same problem in a different context.
This is partially because the car dealer lobby convinced congress to prevent the importation of cars less than 25 years old. Ironically, they did so using safety regulations, so a brand-new car meeting current European safety regulations is legally unsafe, but a 25-year-old car, complying with what European safety regulations were 25 years ago, less any deterioration in those safety systems, is legally safe.
Most rural routes are served by the USPS-proper.
I doubt they're driving from the passenger seat. It's hard to reach the pedals from the passenger seat. Many mail delivery vehicles in the US are right hand drive; the driver's seat is on the right. I don't know that left hand drive is strictly required by any states, it's more a matter of there's not many models available for sale in the US with right hand drive as an option, and few people order them when available; and importing out of market RHD cars is a chore.
You can (or could) order some Jeeps in RHD, and a lot of rural USPS contractors have RHD minivans (many from the Japanese Domestic Market)
I did see a 'converted' RHD Windstar (Ford minivan) on FB Marketplace, where they removed the driver seat, put a flat platform in, and connected controls with cables and levers. That's an option too, I guess.
The fact that large parts of the world do something without any problems is no guarantee that people in the U.S. won't argue about it endlessly.
Having some of the cheapest and most plentiful electricity in North America, courtesy giant hydroelectric facilities, helps. (Also why it's a major aluminum producer)
As an EV owner, crossing the border into Quebec from Ontario gives me about 5x the charging options. Everything from ski hills to grocery stores are set up with a mixture of charging types it's great. Get a 20 minute DC fast charge while running into the IGA to grab groceries and conveniences blew my mind.
There were a number of good EV charging ideas I saw on my road trip through Canada.
Electrify Canada was overall the best experience, though. No nonsense with installing a stupid custom app and setting up an account. Just tap credit card and go. Got full 150kW that my car can take. No hassle. Ate a burrito and returned to 80%.