"iBook" referred to a laptop from 1999 to 2006. "iBooks" referred to the eBook reader app and store from 2010 to 2019. I'll grant that there is some possibility for confusion, but only if the context of the conversation spans multiple decades but doesn't make it clear whether you're talking about hardware or software.
Sorry, I thought you were saying that they don’t use model numbers at all.
I think you were actually saying that they don’t just them for laptops.