Service 89 brings majority of the passengers boarding from Changi
Airport Cargo Complex to Hougang/Sengkang area, where they can link
to other parts of the country.
Service 2 serves Changi Village which does not have a fixed
density for passenger load.
Seems like you still don't get my point. Let me give you numbers
to work with. Assuming that Sv89 brings in $200 per DD slot in a
day. Assuming that Sv2 brings in $150 per DD slot in a day. So as
to make things simple, we will assume that SBST only operates one
DD slot on Sv89 and one DD slot on Sv2 in a day, and SBST has a
fleet of 1 VO3X and 1 Trident. So now, let's say it cost SBST $50
to run the trident on Sv89, and it cost SBST $40 to run the VO3X on
Sv89. For service 2, it cost SBST $55 to run the trident on it and
again, $40 to run the VO3X on it. This is because the route Sv89
travels on is more suitable for the Trident. Thus what SBST will do
is to put the Trident on a route which cost less to run, in this
case Sv89. The pax load on either service does not matter because
at the end of the day, the revenue is $350. And the cost would be
$90, compared to $95 if the trident was to carry out Sv2, and the
VO3X on Sv89.