Why is there no approval for Non-Approved Training Provider who are able to perform EASA regulatory training?

Because the competent authority or other delegated person described via organization expose such Safety and Compliance or Quality Manager is usually responsible to determine that, the provided training fully meets the requirements “training standards” of the organization itself. The delegated person shall review such a regulatory or vocational training before, when present and after by feedback analyses to proof the expected quality delivered by the N-ATP. Each N-ATP shall follow the training requirements described by Part 147 to safeguard the training performance and the learning subject for the student.

This responsibility essentially accepts that the organization itself is responsible for and manages the competence of its staff to ensure they are able to deliver their required role in the most effective way. (This includes any required recurrent training for example). Those procedures shall be described via the organization expose by an aviation organization.