1. How sure are you? The ones from established manufacturers don't really look substantially different from their diesel counterparts. Unless you're really looking closely you'd have a hard time telling them apart.
2. Electric semi trucks are not ideal for long distance trips, they're more for predictable day routes, so it wouldn't surprise me to not encounter many of them on what was presumably a highway drive.
Similar to cars, it's easy to spot Teslas but other brands don't stand out this much and you really need to know the little details to spot. Same for trucks.
I’ve yet to see an EV that doesn’t have some sort of flush handle design. My understanding is that it improves aerodynamics and I’m sure a secondary reason is “Tesla did it first” and the high tech aesthetic that EVs are expected to have.
This caused a lot of confusion with VW; a lot of people thought the id.3/4 were their first electric cars, because the eGolf and eUp looked so... normal. I'm fairly sure they deliberately said "we need to make it look more electric-car-y" at some point.
These are mostly being sold in Europe, not the US. They're also not particularly distinctive looking, mostly; I'm sceptical that most people could identify one offhand as it passed by.