I say this because from what I see on film clips, the truck had zero outward indications or physical mechanical features that it was a refrigerated vehicle, it was a goofy color that looked like a re-paint job, it had no markings, advertisements, trucking company name on the door or anywhere....or anything on it at all as identification, at least as far as I could see.
Plus, the perp may even have looked muzzie, but then, that would have been "racial profiling" on the part of the police, who then decided to shrug the whole thing off, walked away without putting ANY two's and two's together.....and left Mohammed and his truck to continue on with an uninterrupted road to mass murder.
Leni