1. Ice cream has never been affordable to 100% of US households.
2. I strongly suspect the couple in the article could afford ice cream if they brought less beef, less name brand items, or were just more savvy shoppers.
3. I don't know how you determined that it's cheaper to make your own ice cream, but I would say that's generally inaccurate based on personal experience and a basic assessment of input costs and a reasonable value on your time.
4. If you really feel like ice cream is overpriced, you have identified an opportunity!