I don't necessarily think that a company like BMW would say they've performed the job without it being done but it's not unheard of (though, you could possibly request the old bearings back, not sure)
I think the work done on motorplan or warranty and the work done by the workshop are of different levels of quality. They 100% have to give you back the old bearings (any parts) after a cash job. They don't do this with warranty/recall and motorplan work.
I am 100% convinced (now with documented first-hand experience) that under motorplan they have sets of parts sitting and waiting to show BMW if audited. Who is to say what car they came off? They can show parts from any car for anything non-serialised and tough to get to/invisible without stripping.
As much as we complain about the tuned cars that miraculously continue to have motorplan causing extra scrutiny, we also have shady workshop practices that have caused this when trying to get motorplan approvals these days (asking for endless videos, doing things that are obviously not going to work first and sending the client away so they can complain again.
This is now worse than Mercedes (this is part of the reason Merc ownership was so horrible for us in the end). You're made to feel like an irritation or the problem ALL THE TIME, so ultimately you remove yourself from their pool of clients. I always come across as negative sounding about Mercs but I actually loved them. The new SL63 E Performance and old AMG GT C or even W204 63s/507 are all amazing things to me. Unfortunately you have to deal with Mercedes and it is like root canal with no anaesthetic.
I have a 'customer lifetime value' with BMW Midrand of probably close to R3M. I suppose that is not much these days since they now sell single cars for this price, but I have probably also sent them (very conservatively) about R7M of new business in cars, parts and out of warranty/out of plan work from friends and family. Maybe those numbers over indirectly as well. One of the reasons I moved to Midrand for servicing was because of the TLC from Hevashan when he was there and Deago willing to go the extra mile.
Ultimately as much you can feel like friends and family, you are but a number to both the dealer and to BMW themselves. I feel like if they can say they performed work without the job being done for me who has given them alot of direct and indirect business, they can do it to anyone

While they were very apologetic hearing about it (more importantly seeing it LOL), ultimately the workshop manager can't be on top of every tech and the onus on them to get approvals from motorplan. Coupled with the pressure to get the cars out of the sausage factory means a trusted independent is always going to win out when it comes to the attention to detail and accountability. This impact multiplies for more serious work.