Use the back door! Revisited

Yesterday I had the opportunity to ride on a newer bus. It was not much different from the older busses, though a little less worn and used looking. One major difference though was that each time someone signaled they wanted to get off the bus in addition to the bell that sounds, there was also a recorded voiceover that announced “Please exit through the rear door”. How clever, thought I upon first hearing the announcement. How annoying for the driver, thought I after the third, and fourth, and fifth announcement. But what was really interesting was the impact the announcement to “Please exit through the rear door” had on the behaviors of passengers. Do you think that unlike other busses, the majority of passengers on this bus with the prominent reminder of expected behavior actually exited through the rear door? Of course not! The majority of the passengers exited through the front doors, just as if it were all business as usual. Do they just not care? Is it a learned behavior that I do not understand because I did not grow up using busses? Is it some sort of odd status system? What am I missing?