why do people get irritated when people talk on their phones at restaurants? ?

Because they should be engaged that very moment of enjoying a meal with friends/loved ones and talking to them. or looking around the room, letting the mind wander (thats what i do). instead of staring at your latest post waiting for likes, etc.

Because it's called having manners you 

moron !

Maybe some people don’t like it

Basically, if you're talking on your phone then it means your head is not in the game and that you are not focused on where you are and what you are doing.  Laws of nature suggest something is gonna git ya if you keep doing it, that 'something' may come in the form of people being irritated... 

and people think I am sheltered and inexperienced and have no clue about reality when I've never even had and used a cell phone for more than a month.  Tsk-tsk. 

Actually when you use your phone you are talking louder than you realize!

Right! You keep your voice down?

Just like my wife, I tell her I can hear her talking on her cell phone  from greater than 1/4 mile away while repairing a distant fence line.

She replies, "It's the wind carrying her voice"? 

Essentially it's not that YOU are rude but the general public IS! You are collectively grouped with the public pattern.

My personal gripe is entering a business and being interrupted and displaced by someone phoning the place of business and not placed on hold or instructed that they will be called back.  I turn around and leave that business.. and do not return!

 Some people do tend to speak loudly when talking on the phone. People pay good money to go out to eat, be served and enjoy the meal without listening to someone's conversation that means nothing to them. If you are going to speak loud and let everyone hear all of your business then expect that reaction. 

 I have stopped what I was doing like shopping and stood next to some stranger talking so loud, I just sit and stare at them, uncomfortable they either shut up, hang up or walk away. Fine with me.

Because people on Mobile phones don't shut Up they shout into the Phone they don't put it on silent mode they believe they are so important that they Must annoy other dinners

I don't own a Mobile Phone Not that Important that i need to be contactable 24/7/365

so anyone who has a Noisy Mobile is a Bloody Nuisance anywhere

I went to a Nice restaurant Its phone Rang 7 times in 10 Minutes i asked him to put it on silent mode Got abused asked for the Manager got told he could do Nothing I left 6 months later saw a for sale sign on Restaurant maybe if he had some customer service and care they would still be in Business

Last Time I was in Hong Kong Purchased a Phone Jammer so it is silent for 50 Meters around me when i am in any Restaurant Aircraft or Train 

Yes, you are louder. Also, there is no rhythm to the conversation for those within ear-shot, even though there is for you. And no one cares what you're talking about; they just wish you'd shut the fvck up. 

And it is "my talking," not "me talking." Learn to write English correctly rather than blabbing on your phone in a restaurant. 

They are annoyed because they can't hear the other half of the conversation that they are trying to eavesdrop on.

Older people find it annoying because they see the phone as an addiction and people can't even put the phone away long enough to have a peaceful meal.

No one is so important that they need to be on the phone in a restaurant.  If the call is that important - you probably don't have time for breakfast.

If you are with a group of people while doing this - it is rude to be on your phone when you have other people with you.