Public transport is an important mode of travel for all Singaporeans and is usually crowded (Allow pets on public transport, by Miss Irvin Ong Fei Hui, Aug 2).
To allow pets on buses during off-peak hours will put additional safety considerations on the drivers.
The bus drivers' priority is to concentrate on driving safely and should not be subjected to such distractions.
I have had on occasion uneasy experiences of dogs coming close to smell my foot and barking. I would feel uncomfortable sitting close to someone with a pet in tow in a bus or train.