Product placement became common in recent films. It adds a little income to the movie studios, when a commercial product is shown in a movie.
In The Broadway Melody, Hank washes her and her sister's stockings in Lux soap (I can't tell if it's the powder or flake form being used) in the 1929 movie. Lux was a product of Lever Brothers, sold since the early 1900s in the US.
I wonder if there was some kind of cash payment to MGM for this.
E pluribus unum
You can bet on it. How many times have you seen a movie showing Times Square in New York that did not have signs for Chevrolet and Planters Peanuts?
Most movies that feature cars — for years — always use the same brand. I personally have known people from General Motors, whose sole job is to place vehicles in productions, and make them look good.
Back in the day, you couldn't buy a ticket to a movie without getting a free Hershey bar, and a pack of Camel cigarettes, and some Wrigley's gum too; if not a box of dish ware at a raffle.
Odd thing is, you watch cowboy movies and such, and they go to the bar and just order beer or whiskey, but never state brand names. From what I understand, most of the brands used then are still popular today; some kind of a long standing taboo to name names.
As far as alcohol products go, I'd say most beer and whisky drunk in the "old West" were locally made and small batch. Many German immigrants in the 1800s to many states brought beer-brewing know-how with them and set up shop where they settled.
Same for the Irish/Scots who brought their knowledge of whisky/whiskey production and distilling with them and also set up shop when they made their new home. Grains were plentiful on the prairie and all it took was the technical knowledge brought from Europe to change them into drinkable alcohol.
I don't think many alcohol brands of yesterday are still popular today, but I could be wrong. Also, studio heads didn't want film censors to force deletion of scenes with promoted alcohol brands to "protect the children".
E pluribus unum
I do know that brands like Budweiser and Jim Beam were well known in those days, among others.
The reason that Kentucky and other states became so well known for liquor production, was because it was a way to convert corn to a salable product, and easy to transport. Whiskey and bourbon need time to age in barrels. I can grant you that if all they wanted was moonshine, an "old west" place may be able to make do, but they weren't that primitive.
Beer production needs large pressure kettles, supplies of corn and hops that may not have been easily available, and as I stated in the earlier post, these brands were well established, better than Coca Cola at the time.