Here, we're a rural enough area that we normally have PD on calls with us. The dispatcher will do everything possible to get a PD, SO or HP with us for calls on the highway or about Greyhound. (We get a good percentage of our calls off of Greyhound.) In those cases, we have the LEO search the bags that are questionable. We've had our PD offer to help by staying behind with the bus to bring bags from Greyhound so we could transport the pt faster. In those cases, the PD states that he can not leave the bag in the ED without making sure that there are no weapons in it. It takes it out of our hands.
I've rarely been worried about weapons, but I'd be more than willing to ask someone if I were and go off of their reaction. I also make sure that their bag is out of reach during transport by putting it down in the doorwell for the side door. They can see that I'm no where near it and they can't get to it either.