Why the need for the 'thank you very much' style rantette then?
With a degree of conjecture, the conversation went a little like:
"I'd like 4 adults and a child seat please"
"We don't have child seats."
"OK, the last firm did, but whatev's - can we bring our own?"
"You don't need a child seat. Taxi's are invincible to crashes or something, so you kid'll be fine. If he's small, he can fit in the glove box"
"I think I'd rather the heir to the "DrP empire of steel and majik (TM)" travel in safety, thank you very much....."
They charge a fiver to hold onto your seat, or drop it back, or something...
My initial surprise was the idea you don't need a child seat in a taxi.
Not that some lowly serf has failed to entertain the idea of providing the fruit of my loin with some jewel encrusted size appropriate bucket seat...