Quite true. I believe a part of the job is just to advice passengers, but anyway as the "bus" rides only at a very low speed over a short journey (500 m back

Quite true. I believe a part of the job is just to advice passengers, but anyway as the "bus" rides only at a very low speed over a short journey (500 m back and forth) it wouldn't matter that much even if the attendant fell asleep. And a part of it is surely just to convince the potential passengers (who don't have to pay anything in this trial) that "it's safe, we even put our own guinea pig to prove it".