Sometimes it is not convenient to buy a bus pass as you do not use transit enough to break even compared to single ticket prices. Single fare passes and the 10 pass booklets are priced much more expensively per ride than a bus pass, the price per commute with a bus pass goes down with every additional commute. However if you only use transit a few times a month the single fares are beneficial. You could buy a 10 pass booklet and use one only when you need to. It is common with transit systems around the world for the single transit fares to expire after 90 minutes. Once you board a bus or train you have to have it stamped to indicate the time that you got on, thus the clock starts ticking. It does not matter if you only ride the bus for 10 minutes and then hop off to wait 20 minutes for another bus. Those 20 minutes you waited for a transfer according to transit authorities, count as using transit.
Having one blanket price is highly impractical if you need to do a series of chores at different corners of the city one day, but you do not use transit enough to justify the cost of buying a bus pass. If your chores caused you to spend an hour at a doctors office after only utilizing the system for 30 minutes, you will have to use another fare for the way back. I would like to see a fare system installed that would help decrease the costs if you only need to use a bus for 10 minutes. With the current systems 10 minutes on a bus only utilizes 1/9 of the time allotted but yet you still pay 100% of the fare.
One solution is to break the city up into zones similar to what is implemented for Vancouver's transit system. Fares would be priced according to the number of zones that you would have to cross. If you only have to travel within a certain zone the fare would be the least expensive, if you have to pass through two zones the price is slightly higher than for just one zone. The price would continue to rise for each additional zone that you would need to cross. This way those that need to travel farther have to pay more, this makes sense since they are using more energy since they are utilizing the transit longer. This helps decrease some of the inefficiencies with the single fare system, however people are still losing money when they have to walk to another stop and wait.
Possibly in the future we can have smart phones, or fobs outfitted with a signal emitter that allows the transit authorities to track the time you were physically on the bus. When you board a bus or train there is a receiver that receives a signal that is being emitted from your fob, similar to what offices have installed to open doors. This transmitter would be able to pick up your fob's signal when you are on board, and once you disembark your fob would leave the range of the transmitter. The transit authority would then load the commuting time onto your online transit account. This system would have to utilize GPS on the bus as well, to ensure that time spent stuck in traffic could be deducted off of the bill.
This sort of system would also help increase efficiencies since the bus driver would not have to wait for every person to show their proof of payment, you could install the sensor in the doorways of the vehicle similar to a metal detector at the airports. The door sensor would alert the driver if someone without a fob has boarded the bus. This sort of system would reduce wastes and costs to the transit authority since they wouldn't need to provide paper fare booklets, transfers and bus passes.