I don't remember anyone talking about a cap on the number of TNCs, you may be confusing that with the very large outcry over a cap on number of drivers. From memory (of the original bill) the drivers are able to get the full for-hire driver license with more intensive testing and then the 16 hour cap doesn't apply? And uber/lyft/etc all refuse to say how many drivers they have now, so fuck 'em, 300 is probably enough.

edit: there might have been an argument that capping the number of drivers would de facto prevent new companies from starting because all the slots would be taken by existing ones?