Besides Sofia, if you're using public transport in another Bulgarian town you have to buy a ticket when you're already in the bus. There is a person who constantly goes back and forth around the bus and sells tickets to the new passengers. (Imagine what a boring job!) So as my sister says "I love Sofia public transport because it's the only one in Bulgaria that is free." Тhe choice "To buy or not to buy a ticket" depends on what kind of person you are. If you are a model citizen and always follow the rules just buy a ticket. But if you're more likely a rebel at your heart and you believe in the motto "F**c the system or the system will f**c you" so just don't bother buying a ticket. I personally think that the charging method in Sofia is fundamentally wrong. There are so many charging methods in other countries which are much more effective. So why don't we just borrow some of them? Not to mention that Bulgarians are so creative when it comes to cheating. So come on Sofia Public transport - challenge us!