This kind of job should be left to the bus conductors.... The bus driver should just drive the bus and stop being so kay-poh.
If SBST is really so "gan cheong" about $$$, why not make the passenger pay a heavy fine? In many other countries, there is a heavy fine for those who are caught not paying. In my opinion, a heavy fine is a good way to discourage people from not paying, and it also complements Singapore's image as a "fine city".