Yes, COE premiums got nothing to do with drivers....
BUT...
If they (comfort) failed to secure the COE for their taxis,
then, even you are willing to pay $200 daily rental also no use.
correct ?
so, it is still the chicken and
the egg problem.
Let's create a
scenerio.
Previously, a e220 cdi may cost $125k + COE
($25k) = $150,000.
@ current, a e200 or 250 cdi may cost $150k +
COE ($52k) = $202,000. which meant the breakeven point for
the company may take longer or increase the rental accordingly.
If the COE surged further to $70k, which means the rental will
have to be adjusted again.
The company's concern is that, at a higher rental, can the
drivers managed to survive or returned back the vehicles to the
company after a few months ? It is not a few hundred dollars
deal.... It could be a few millions of dollars investment.
Got my point ? The market leader is alway kia si. 
We understand the basis of COE. But didn't the rental inclusive of
many factors and not just COE alone. Diesel, road tax, insurance,
maintainence..etc. Comfort using existing scrap vehicle's COE to
replace a new vehicle. So definitely they have the sufficient COE
to replace old vehicles, simple logic, one to one exchange only. Is
just too bad that this period the COE price escalate too much, so
to factor this different to current pricing, is really not fair.
For Prime is different, they waiting for LTA allocation of COE to
bring out the new taxi, so they are at LTA mercy hand. Maybe we
will see another round of $50 COE, remember? That month, so
coincidence, Comfort came out the first 100 big/small headlamp
mercedes.