Well handing out Tootsie Rolls is certainly not what I had in mind and when you post absurdities such as that, it tells me that you are not here to argue the subject intelligently.
Here's another thing law enforcement can do to diffuse the situation. If they have real good reason to check out white vans, they should just level with the public and lay down some ground rules. For instance, they could state through the media that during the next roadblock, anybody driving a white van should step out of the van with his hands in clear view when approached by a police officer.
I'm not fond of that approach either but at least it gives the occupants a chance to comply with the search without having to be tossed into the street at gunpoint and handcuffed.