If you're a large company that's actually serious about security, you'll have a Red Team that is intimately familiar with your tech stacks, procedures, business model, etc. This team will be far better at emulating motivated attackers (as well as providing bespoke mitigation advice, vetting and testing solutions, etc.).

Unfortunately, compliance/customer requirements often stipulate having penetration tests performed by third parties. So for business reasons, these same companies, will also hire low-quality pen-tests from "check-box pen-test" firms.

So when you see that $10K "complete pen-test" being advertised as being used by [INSERT BIG SERIOUS NAME HERE], good chance this is why.