UPS trucks are custom designed for UPS; they used to have a nice documentary about it. New Amazon trucks around where I live are clearly custom (and also not very pretty, if you ask me).
I saw a Rivian mobile service van for the first time about two weeks ago. I was behind it in traffic. It’s exactly the same design as Amazon, just different paint.
All I could think of was “they repainted an Amazon van“.
I know Rivian makes them all. But seeing so many Amazon vans has changed who “owns“ the design in my mind.
Perhaps the next generation of UPS trucks will have large windows like the new USPS trucks. If it seems to be a useful feature, others will adopt it eventually.