how do enterprises actually enforce llm usage policies across multiple teams, models , and providers?

like when you havee multiple teams all using multiple models from different providers for a number of use cases . who decides what is allowed. how do you acutally enforce it. and how do you know whatever rules you put in place seen a few approaches come up. some team are doing it through the gateway layer . some through internal policy docs that nobody reads . some through access controls on api keys. some just hoping for the best tools that come up in this context. orqai , portkey , azure api management , aws bedrock , langsmith portkey gives access controls and budget limits are there , poli