You're correct .While reliability may not factor into the criterion,brand identity sure will.Very few shooters aren't at least passingly familiar with Glock, and many folks walking about the gun store aisles are Glock owners.
When folks buy a product, good experiences with the same firms other products beforehand will go a long way to ensuring another sale.Think of all the millions of Glock pistols in circulation, and imagine even half of those customers shopping for a .380. That's a cash cow for the Austrians.