Taxis is classified under private public transport, you can flag
them down at most places, you can state/demand your destination,
you can also command the road..turn left, turn right..and more
importantly, you can complain until the top.
Other public transport like bus and mrt is meant for safety and
orderly. As long as there is more than 2 and above different people
taking a public transport, camera can be install to monitor the
situation for safety and orderly reason.
Different people imply stranger and peoples who do not know each
other
Taxi is either single or with someone they knew or in group of
relatives, colleagues or friend, therefore, it is deem a single
entity, there is no need for orderly and human interacting safety,
and therefore putting up a camera on pax is consider an intrusion
of privacy.
However, like cdg, in emergency, there is a camera