Well, you can negotiate and remove certain phone screens based on your experience, although the on-site would be more or less the same for everyone. Further, Amazon RS / AS, SDM, and Google RS loops involve very little or no coding. Instead, there will be a presentation round. For Apple, they follow team based hiring, and most don't involve DSA and based on your experience. For instance, if you're an engineer in Intel, Apple likely hires you.
As for removing the DSA for existing FAANG employees, guess companies don't trust supposed accomplishments and would rather go by DSA as they offer top pay. If say, we started treating pedigrees as important criteria and remove DSA, then there will be calls based on "education" based on advanced degrees, publications, etc. Companies don't want to change and would rather have identical process for all