Likewise, I probably haven’t seen an ad for coca cola or kleenex in a while. Once a brand is ubiquitous to the point where soda becomes coke and tissues become kleenex in the lexicon, it feels like ad spend is wasted.
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.