They mostly do it from inertia, how well it works is a separate question. Historically you can find many examples of hugely successful advertising campaigns, it’s much harder to quantify the negative.
I think both Uber and CocaCola has a lot of work to do until I like any of them. I like CocaCola as a product though. Never tried Uber. For example I really like some Nestle products, but try to avoid them because of their bad company/brand reputation, even if their product is both cheaper and tastier I buy from a competitor instead. Whatever a company stands for and how they act will affect their brand.