That's a little bit different. The brand names demand higher prices because people desire them more. It's not a result of the cost of advertising, but of the effects of advertising.

The generic isn't cheaper because it didn't spend money on advertising, the generic is cheaper because if it were the same price as the brand name, you'd buy the brand name. It is my firm belief that Kraft (aka Mondelez) has been getting away with selling garbage products for at least a decade now just because the brand is so strong.

The differences between name brands and generic brands is not purely advertising. I will grant you most of the difference is marketing, but advertising is just one piece of what falls into marketing overall. There are plenty of brands that don't advertise and still have a strong and prominent brand identity. Sometimes not advertising even becomes an element of that brand identity.