I don't think this takes away from the point that big corporations use their massive marketing budgets to create demand beyond what the quality of a product might warrant. The smaller you are, the more you rely on the quality of your product. Being big doesn't mean you can make a crappy product but you sure have more wiggle room to cut back on expensive ingredients.
"Marketing" is why dumb people buy stuff you don't like. "Quality" is why you buy stuff you like. I think it's pretty condescending to tell people "You don't actually like that, you're just a rube."
Maybe other people like Bud even more than their marketing might "warrant"? Maybe you like Dogfish Head more than the quality "warrants"? There are tons of small breweries that are successful because they position themselves well (we're the cool guys, anti-corporate, local/whatever) and make pretty bland, middling beer.
However, that cost of sales is a compound number. it is ingredients, labor, packaging. so marketing is roughly 30% of the cost of everything else involved in making beer. Still pretty high no?
Cost of sales includes depreciation on property, plant and equipment as well. "Marketing" includes basically anything to get the stuff from the warehouse to the consumer. Beer is heavy and perishable, logistics for such products are very complicated on a global scale, so there are a lot of expenses incurred under that category that don't have anything to do with Super Bowl commercials or Clydesdales.
Edit: technically receiving and storing beer in warehouses can be capitalized into the cost of sales. So inbound logistics, handling, and the appropriate amount of warehouse overhead would rolled into the cost of sales, and all outbound logistics would be part of the selling expenses.