Drivers/company will put off supplying car seats as they are not obliged to do so. They don't keep them in the cars at all (theft risk) so a call fit a taxi plus seats requires driver to go out if their way to go back to base to collect seats, pick up the fate, then back to base to return seats. They don't get paid, and actually lose money for the time to go back to base and install seats and then return and remove them (fuel costs etc) so most will say no to the fare. The only obligation is to provide an anchor point for you to use I think

I know here (small town) bookings asking for car seat are not high on the list of wanted jobs by the drivers. And base is, at worst, 6km from a pick up in town. None of the drivers have an issue if you use your own though. If we are going to be out where we need to taxi it home we pull the seat out of our car and put it in the taxi. Takes about three minutes. Drivers are usually helpful with dropping seats to get to anchor points ( we only have station wagon taxis here)