Etiquette Question

I vote not rude unless the questioner is waiting for several minutes. But perfectly reasonable to wait for up to a minute. The questioning person is not the center of the world. And it's reasonable to ask a reading/viewing person a question. 

And this applies to adults as well as children, a book as well as Tik Toc.

I think it is fine for someone to want to speak to someone who is reading or on line on their phone. I think it is also fine to ask the person to hold on a sec.

My initial reaction is - how hard is it to stop what you are reading or watching on your phone to look up and respond to the person??

I would assume the people sitting in the room know each other or are related and to me, its is just natural to think of something to say or ask a person that is sitting in the same room you are in. I have no problem being told to wait a second if I ask a question to someone doing something else. But I do think it is petty if someone gets irritated if they are asked a question while watching videos or reading. Some people's noses are constantly in a book or phone, so how do you communicate? Ha!

Now if I was in a room with people I did not know or barely knew adn I saw they were reading or doing something on their phone, I would not interupt them.

For me this would depend a lot on the circumstances. Relationship between the two people, how often they're asking, how easy the reply is, and most importantly what they're interrupting for. Is it a "Oh **** there's a huge wasp in your drink, be careful!", a "I need to know this now for time sensitive reasons", or a "I just want you to pay attention to me/this thing I'm interested in."

"Do you want potatoes or rice with take-out?" Easy, time-sensitive, I'd never be annoyed for someone interrupting with this kind of question.
"Hey look at this cool thing I found." Potentially activity ending, probably a lot more involved, requires full attention, I'd likely ask to wrap up what I'm doing for this kind.

If it's the latter then it'll depend, again, on how much you value the relationship of said person and how often they do the interrupting behaviour. There's one person I know who does this constantly when there's a conversation or activity going on between other people and it's incredibly annoying/rude. One thing if you want to join in, great! Quite another when you try to wedge your own activity/interest into something that's already in progress.

It’s sort of an unwritten rule in our house to say something like “let me know when I can ask you something” if the other person’s interest is elsewhere.

So, side with you - as long as the “interruptee” is polite with the “hang on a second - just want to finish this.”

I think since you now know that the person thinks it's rude of you to keep reading/watching that it might be a good idea for you to pause what you're doing and listen to what they're saying. In general, I don't think it's rude of either person, but in the case you've mentioned, I'd just go ahead and pause what I'm doing. Not a hill I"d want to die on so to speak.

If I had waited to interrupt eXH, I never would have gotten any response as his nose was always buried in his phone, likely talking to his homewrecker GF.

There is not enough info

2 people in a waiting room who don’t know eachother? Interrupter is very rude ( unless it’s the staff I’m waiting for & then no way would I tell them to wait a minute ) If I don’t know you, don’t bother me if I’m occupied unless there is an emergency. I ‘read’ in a waiting room because I’m not up to talking to people I don’t know. It’s the modern symbol to tell you do not disturb.

My direct family I live with? I would not think the interrupter is rude as long as they are polite about it. Making my family wait anything longer than a minute ( a valid minute ) for tick tock or other internet scrolling or even an e book or book is rude, imo. There are book marks for a reason. Put it down, give them your attention, see what they want, then determine if you need x time to attend to what they need or can do it right away. Ignoring your loved ones for your phone is rude. At least pause to acknowledge them and see what they want.

Reading in your computer for work, working, or an online class ( even a recreational class ) most especially if the class is live then I’d look up and say I’ll be done at x time or in x minutes this is work or this is a class.

Courtesy & respect is a 2 way street.