There is a shuttle van service between Sky Harbor Airport and Tucson. Could be one of those.
Wrong side of town. This sounds a ways West, like around Tonapah.
I lived in the Phoenix area for over 40 years before moving to Florida last year. The accident occurred on I-10, 60 miles WEST of Phoenix. Tucson is 100 miles SOUTH of Phoenix. So your speculation is incorrect.
I-10 is a double lane divided interstate highway. How did a semi-tractor trailer cross the wide no-man’s-land median between the divided highways? There needs to be more details reported before we know who the occupants of the van were and how the accident actually occurred.