On a recent trip to Amsterdam, my husband and I traveled around the large metropolis using its famous tram (all electric and an older version of our San Diego Trolley). All riders use a rechargeable card or app with loaded fare. There are no kiosks at stations, but each train has a small device mounted inside by the door for everyone to easily scan their device when getting on and off. And if you don’t, other riders will remind you — in Dutch! It was often standing room only, but the system worked well.
Why can’t San Diego try this? The cost would be quickly recouped by increased fares collected. The conductor of each car was also accessible to passengers (like a bus), which discouraged vagrancies and littering.
— Nancy Nevin, Rancho Peñasquitos