So in my opinion marketing in the digital era is more efficient by relying on social media rather than TV and radio or others.
It still depends on your audience. If you are selling the product for young and between 30-40 years old people, then advertisement on social media is much cheaper and brings more result but if you sell the product for mid-age people (40-60 years old), then TV or Radio, depends on the country and the city, might be better than advertisement through social media.
That's a good point. Since most elderly people don't want to use gadgets for the reason of having an older age, they prefer to do what they used to which is to watch television or listen to the news using the radio. They find it more relaxing and easy to use compared to using a gadget and browsing on different social media channels which they don't easily understand.