Advertising creates a disincentive for trying unknown products. Combine this with brand loyalty from good PR, and you keep control of your market share.
This is well illustrated with Ironbru in Scotland. Lucozade and Tango in the UK in general. The introduction of Fanta into the North American market too, I knew it from the UK and one of the last flavours introduced was actually Fanta Orange (the most popular one in the UK, direct rival with Tango) due to the saturated market for that type of drink.
Because advertising typically reinforces a products quality. Why would you try a no name brand when you buy Heinz who is the leading national brand.
If you have a vending machine selling Coke, Pepsi and Joe's Discount Soda, you're going to go with Coke or Pepsi.
Personally (here in Canada) I prefer the Noname brand baked beans over the Heinz brand due to the Heinz brand over using the hickory flavouring. However, this is because I grew up in the UK and the Noname brand in Canada tastes exactly the same as the Heinz Baked Beans formulated for the UK market.
I actually continued to buy Heinz Baked Beans for a couple years before I finally gave in and bought one of every brand to get one that tasted like I was used to.
If it wasn't for the advertising I would have likely bought a different brand of beans within a month, not within a couple of years. Why? Because Heinz is the best, surely the others must taste worse! Since then I always try the store brand and lesser brands
This is well illustrated with Ironbru in Scotland. Lucozade and Tango in the UK in general. The introduction of Fanta into the North American market too, I knew it from the UK and one of the last flavours introduced was actually Fanta Orange (the most popular one in the UK, direct rival with Tango) due to the saturated market for that type of drink.