In my experience, the bus riders are orderly and polite. I have not seen grafitti on the buses.
Most streets are narrow and congested and buses are definitely king.
Add to this vehicle soup mopeds, motercycles, bicyles, ancient cars, brand-new SUV's. I remember my first bus ride in San Jose, I had exact change in my hand as I stood under the plastic roof ready to board. I climbed up the stars, handed the bus driver my 55 colones, and entered into anoth er world. It seems like all kinds of people ride the bus in Costa Rica- students, parents, babies, businessmen and women, as well as people of little means. Although I am ashamed to admit, I don't think I would ever ride the bus in San Diego.