It is a fact that taxi is used by public users. It need to take
into consideration of other public users taking the taxi.
Eg. can pax bring durian into the taxi? Can pax vomit in the
taxi? If fetching dog need to clean up after they alight, it is the
same thing like pax vomit in the taxi.
As long as the pax action will affect other public users, there
is a reason why TD reject the request.
If pax brings dog into taxi, it's the pax, dog and taxi driver.
If pax brings dog into MRT or bus, it's the pax, dog and a
hundred other people of all races, religion, age and sex.
Thus, in an MRT or a bus, it is a direct contact with the dog
and many many other people. That's why it is not allowed.
Yes, if you are so particular about such things, you can clean
up taxi after pax alight, just like vomit.
Based on your reasoning, we should stop selling bak kut teh in
hawker centres as the customers will spit the bones on the tables
and it will affect others...lol.