If you studied Marketing in college in the 1970's you had a course called "channels" which covered the manufacturer to consumer options. One of the really sobering exercises we had to work on was the distribution costs. The "last mile" sometimes costs more than the whole distribution chain for the product to reach the final customer. That's why Amazon is building out their network of trucks. Expenses have caused the Postal service not to renew their Amazon contract. If you read the Aldi website the prices for delivery "item pricing may vary". I can guarantee you it won't be lower than what you would pay to buy it in their stores. Kroger tried online no stores in Florida and failed.
Economics is built on the principal that consumers will gravitate to the "perceived" best value.
And value includes the non-tangible items such as ease of purchase, trust in the merchant and even the neighborhood where a particular store or outlet is.
This is one of the issues that has always affected... perhaps "plagued"... radio: we are the messenger. We don't establish the nature of the seller and we don't create needs with consumers. We just carry a message.
If I am not buying a new car, I have no interest in car ads. And if I'd never buy a pickup, I have even less interest in that type of car. All the ads in the world will not change this. And if I
am buying a car, if I've heard bad things about a vehicle or a dealer, I will ignore or resist ads for such options. Or, if I am buying cash, I will be annoyed by the "Only $199 a month and it's yours" advertisements.
This one example is to show that the evaluation of any ad medium depends on the needs and wants of consumers and the ability of vendors to satisfy those needs.
The only place that radio does a horrible job consistently in all this is when the station that got the buy writes copy with no time or interest in doing anything creative or motivational.
On the other hand, a few days ago I heard an ad on a local Palm Springs market station for a pet grooming service. The owner voiced the end of the spot, saying, more or less, "I'm Bob and I'll make your dog beautiful and happy. After your first visit, ask them how they liked it and I'll bet they will love you for it!" It ended with an affectionate barking sound. Stupid? Maybe, but simple and real. Somebody realized that just repeating the phone number over and over won't cut it.