I'm confused at your comment. The point I saw being made was that passing the Federal Safety Standards was the last major hurdle before they could bid on Postal Service supply contracts. And that their vehicles had passed the testing. It doesn't appear relevant who does the testing, the relevant part is that it's been done and it was successful.
Tl;dr; PR is PRish.
True, the Postal Service is looking for commercially available vehicles, so production and certification are gating functions.
My comment was related to idea that it was a "major hurdle". To me, that implies some difficult task that weeds out lesser manufacturers from greater. In reality, it's like a rubric in a high school class, if you do these 5 things on a take home, open book, no time limit test, you get 100%. The crash/ impact test are the ones that might require a late stage redesign if starting a design from scratch.
There are other FMVSS qualified pure electric delivery vehicles put there, which is why the press release said
making Workhorse the only American all-electric OEM designing and manufacturing last mile delivery vehicles to complete this testing,
The testing isn't the unique item there, it's limiting the scope to: American manufacturers that only make electric vehicles. So the Freightliner based Daimler
eM2 (pilot vehicles on road since 2018, production next year) would not count (per WH press release) since they both also make non-electric vehicles.
I also don't get how Workhorse can call themselves all electric, given their previous range extended W-15 pickup
A $52,000 plug-in electric pickup truck w/ range extender receives over 5,000 fleet orders, opens reservation to the public - Electrek and fuel cell delivery van
FedEx Takes Delivery Of Workhorse Range-Extended Electric Van
Either those concepts were canned or electric only refers to the final motive power.
Back to testing, the C650 and C1000 both are 12,500 lb gross vehicle weight rating, which puts them in the over 10k lb group (like most delivery trucks). This exempts them from a bunch of tests and requirements (no airbags required).
Expected range is 100 miles on the base battery pack
Workhorse ready to run with C-Series electric delivery van - FreightWaves