I used to have an Aprilia motorcycle and 3-4 times every year I got a Service Bulletin from them with technical upgrades.
It was stuff like starter gears needed to be updated etc - parts and labour all paid for by Aprilia. Aprilia (and other bike manufacturers) always develop their models and when a fault or an malfunctioning part is located, they issue a fix.
But what about BMW in general when the car is "out of warranty" and have BMW ever issued a "Service Bulletin" (dare I say recall?) on the X5 E53 models?