These situations are often true.
The solution is to understand the big vision/direction in-house (even then, enterprise can turnover & new people often don't know the history). Then send out for the best "whatever" you need. Hire a few different consultants in different areas & get second opinions. More work (to manage), lower risk, more in parallel, constant feedback/results. Force consistency.
Large corps can often partner with OEMs or use specifically recommended providers (often ex employees of said OEM). Nike can call Apple for example. Depends on the size of the business/project/integration if this is an option.
Honestly, a lot of it can be common sense, standard practice & pretty straightforward too. As it is a big money earner (for anyone doing the work) there will be layers of 'abstraction' to increase the value of the service offered to the enterprise. There can be a lot of risk (depends on the company/product/tech/maturity) or it may be imagined risk.
Tech companies tend to try to behave like startups (it works) & this may be a good way to go (risk/legacy dependent).
It all depends on product/goals/resources & in-house knowledge/skills really.
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