But they are totally different situations. One is an emergency, one is possibly rude. Why discourage parents from going to your restaurant by charging them more? Why is it a good idea to go backward a decade in safety?
Then why carry a phone at all? We survived thousands of years without them.
So why does it bother you if someone talks on the phone, if they are not in your party? How is that different than them talking in person at their table. Really, this is about your feelings, your reaction to something. There is nothing inherently wrong with talking on a phone. But like much of life, it is about your reaction to what others are doing.