Using your examples, there is nothing stopping people from the opposite political leaning from reading that certain newspaper (and many people do read newspaper

Using your examples, there is nothing stopping people from the opposite political leaning from reading that certain newspaper (and many people do read newspapers covering both sides). Same with 6am radio - there is nothing stopping under 35s listening (and indeed there will be many that do). With FB adverts, it is a complete 100% filter if you are outside the demographic range. You have no choice in the matter as to whether you see that material or not.