[kysol]

We do, not 100% of the time, but damn close (usually non-locals and jerks that will push in past those coming off).

As for Japan, I was amazed when taking the trams down in the south where, from what I remember, you got on via the back doors (taking a ticket, which was optional some times depending on the trip), then you would slowly move forward to the front to pay on departure via a coin collector near the driver. Change machines were also on the trams. The ride and transaction was seamless as everyone always had correct change, the collection of money took little to no time (we're talking nobody really stopped, drop money in, keep walking) and because everyone was entering and leaving the assigned doors, everything just worked.