He's asking why the fare so cheap.
Let me give an example, let's say i take from woodlands to
jurong, probably it reach my max fare which is 58cents. Then i
transfer to another bus, the fare for that bus trip will be free
(zero cents). For students, no matter how
long you travel, you'll only spent
58cents.
But take note, the max transfers you can make is 5, after that
the fare will reset, though i hardly meet anyone who make more than
4 transfers.
On top of that, there's a limit for the whole journey to be
completed within 2hours, and 45 minutes allowance between
transfers.