I have been riding a tadpole trike since 2012. Much is on MUPS in town, but a fair amount is on streets to get to where I want to go. Not in all that time have I ever come close to being hit, or had a close pass. Drivers seem to stay clear of the trike. As stated many times it may be that drivers seem to think they may be some sort of handicap device, and dont want to have their picture in the paper as the scum that hit a handicap person.
Along with that as others have stated, have and use a mirror, wear a helmet, and fly a flag. Then clip in pedals are needed for safety, especially on tadpole trikes.