Probably because Charles is Head of State of 15 countries, while Harry is the unemployed husband of a small time influencer? I can easily see what Harry and his wife would have to gain from recording an interview with the King, but not the reverse. There's also the fact that only one 'side' has a track record of divulging private family conversations
I prefer to think that a 15-minute video call, once a week—to perhaps have a laugh about what you’ve been up to, Pa; Harry’s latest surfing pictures; a birthday party the kids went to; or the next chapter of the book the King is reading to the children—wouldn’t have anything in it to raise eyebrows, even if it were recorded and sold to the press.
Or do people really think the Head of State of 15 countries, whose life is about small talk and diplomacy—being careful what he says—wouldn’t have it in him to keep such a video call on track.
Why are people assuming the video calls would be like walking in a minefield when the reality is there are so many ways to do estrangement, especially when young children are caught in the middle of it.