Because it is fit for DD service, i guess.
Off topic, this evening i noticed that both sections of the
Volgren B8RLEA seems to be equally long. Maybe can negotiate the
curves in CGA basement?
Why would you say they are fit for 800? 800 high loading comes
only in first two stops along Yishun Ring Road, where you also have
svc 804. After that bus usually has lesser than 20 pax as it serves
as mere intra-town service.