Most trucks have a 55mph speed limit on public roads, including highways. Based on my experience with truckers and the small business of trucking, it was probably the state, local, and manufacturer incentives that made that truck affordable to purchase/lease. As long as the operating cost is less than the gas equivalent, you're good to go. Probably a current design with just an electric powertrain, not a ground up new vehicle. The BYD, Volvo, and Freightliner trucks are hard to tell at first glance, compared to Tesla and Nikola.
Why optimize new stuff for aero efficiency when existing stuff from the parts bin will do the job.