Sorry, but you are in fact wrong. LEGO is the brand and they produce building blocks or a building block, singular. The term LEGO’s is a slang bastardization that has made its way into popular culture, albeit wrong, it is still slang and is not correct. If you are going to act as an English authoritarian, please do you homework and fact check first. Also BMW, Bavarian Motor Works has an “s” at the end of the proper name, and that is why you might see it referenced in both forms.

Well, not exactly. LEGO is the brand and building blocks are the product they produce. “LEGO’s” is a slang term, bastardized from incorrect usage.