My sister responded again:
I got the point of difficulty in monitoring. In fact what I was particularly wondering is how to make people that use public transport, regardless of being poor or rich, pay bbm/liter less than those use private cars. The justification made is simply that people using public transport use up much less space of the road and do not get as much convenience as people using private vehicle. I am fully aware of the absurdity of effort to identify who the poor or rich are in Indonesia.I mentioned about ticketing for buses through which government gives subsidy to the public transport users, i.e: users buy bus tickets at Rp. X, then the bus operator can reimburse the tickets at Rp X+Y. ticketing system has been applied for KRL (have no info of how it works). Unfortunately, as you said, for ticketing, there is always an issue of ticket faking. Now, what about allocating oil stations for buses where oprators can get cheaper bbm?
To which I replied:
And I told her, please keep stimulating such good ideas; and don't get tired by economists' skeptical starting points in looking at things -- they are skeptical.Nice thoughts. On your last question. We sure hope the bus drivers do not have some evil pact with some guy somewhere: fill up their tanks repeatedly, and go sell somewhere else at higher prices. Arbitrage at play.