Since Meowth was able to teach himself human speech, why are other Pokémon not taught to speak as well?

They all demonstrate a similar level of sapience, and with Meowth as a baseline, they are clearly at a human level.
Plus, all Pokémon have the ability to pronounce their own name.
Taken these two points together, all Pokémon should be able to learn human languages.
Why are there no schools or programmes in the Pokémon world to facilitate this, especially since it would improve communications between them and their trainers?