The Paris Metro lines using rubber tires are almost all retrofitted (line 1, 4, 6 and 11, only line 14 was operated with rubber tired trains from the start).
Retrofitting actually has some advantages for old lines with short station distances, tight curves and steep gradients, whereas new lines can be planned with the limitations of rail technology in mind.
The Chinese have nearly doubled the metros built in both number and mileage in the last two decades. And pretty much none of those are rubber tired either.
Rubber tired metros are also a niche in new metros.
You can't retrofit rubber wheels easily so of course compared to all metros as a new technology it will be rare