You are correct, it is likely because very few, if any, people in Europe cares who BMW buy their oil from.for some strange reason there is never a link for that kind of info in europe.we always know about this only from inside dealerships info.
but there is an announcement for ending with shell:
Shell remains as BMW’s recommended oil supplier | Shell Global
Shell-produced premium engine oils to be used for BMW service-fills until 2022www.shell.com
now on 2023 there was still an negotiation with 2 oil blenders and castrol was the winner again.never heard about which the other one was.so from 2024 is castrol again.
who knows why they don't announce that, you might ask.well perhaps there is an explanation of my own. nobody really cares about bmw oil in europe,most of them they dont care that much about oil generally since bmw told people that their engines can work with neuclear oils for 30.000 km.
The only owners BMW cares about are those who own the car under Warranty.
And for those owners 20k mile oil changes will do just fine.
Maybe it because in Europe we don’t have a fascination with buying the cheapest oil from WalMart?