There is a real problem where it's often hard for poor people to get and prepare healthier foods, but you don't solve that by making it illegal to sell convenient foods. You solve that by ending food deserts and making sure people can earn a living wage while working reasonable hours.
@BathysphereHat People also get it from both sides with the "you can feed a family on pennies a day..." rhetoric which is usually based on bulk buying prices but then they're not supposed to buy the likely more shelf stable and longer lasting processed foods and buying fresh foods cheap usually means you eat them on the day you buy them.
@Spudman101 Absolutely. It's also often based on foods like dried beans that take time and forethought to prepare.