That’s not true, there are many manufacturers that use the same kind of battery and engine. In the Netherlands, most of the bikes I’ve seen seem to use Bosch.
Oh really, like who for instance? So far I haven't seen any ebikes other than maybe the no-brand ones on Amazon that do this. (But I would like to know about them if they exist.)
As I and the other commentor pointed out, quite a few bikes, especially the Netherlands, use the same standard engine and battery system by Bosch.
As an example, Canyon uses Bosch, Fazua, and Shimano batteries.