briefly :
outside of IT, the c-suite and top layers of every functional dept. interact at the UI and analysis layer. let's just say even more superficial criteria can come into play with sales decisions.
i see refusal for 3rd-party more a barrier for new enterprise sales, rather than handcuffed incumbents.

my personal experience with AI (operating on my own private data) within consumer products is abysmal when the model has been developed in-house. a prime example is intuit for taxes and accounting. their AI is not just bad, but a complete waste of time for those that try it out.

the public test most are aware of is microsoft as it attempts to remove openAI within its proprietary products...not sure if they will be good, but at least they have a benchmark.