With ev trucks you lose tons of freight capacity to the battery since the maximum weight of the truck is limited by regulations
The eCascadia has a 230 mile range on a 475 kWh battery. If you make that 1.5 MWh, it'll handle essentially any trip a single driver can make before his workday is over. A 1.5 MWh battery works out to ~17,500 lbs. Subtract the engine, exhaust, and fuel weight from those trucks and the majority of tractor trailers on the road will still be under the legal weight limit.
The largest factor is the lack of charging (detouring to hit a charger is very costly) and the cost of batteries that size.