I don't think it has anything to do w/ "They are more uncomfortable with the face to face, human interaction." We teach our kids not to talk to strangers and people they don't know. We tell our spouses to not allow strangers in our homes/cars even if they are offering a service.

We also live in a culture that false accusations can ruin your lively hood. Even a completely innocent offering of help can result in major problems for people in todays world.