I thought you were supposed to mature with age...?

I know we all have our moments of immaturity but I find some people just act like spoiled brats well into adult hood. 

The sad thing is I am not even talking about persons my age (or younger)...I am talking about people who are well passed 50.  I just don't get it.  I get that with age comes a lack of caring what others think but acting like a scorned tween is just beyond annoying. 

I never expected someone older than me to resort to this kind of behavior.  I had to cancel on something last minute.  I was stuck and couldn't get out of a previous engagement that ran over.  Since I couldn't make a call I sent a text apologizing profusely and suggesting they go on without me.  This would entail driving themselves.  I never got a reply.  So when I was leaving my prior engagement I called.  No answer.  Hmmm, maybe they decided to buck up and drive, cool. 

A few phone calls and texts later I decided they were either dead or ignoring me.  I was leaning towards the latter.  So I sent a text requesting them to acknowledge they were indeed alive and *ding* got a response.  Ahhhhh, I see now.  So we ARE in fact ignoring me.  It has been 4 days and still no conversation...nada.  I guess we are still mad.  I don't get it.  Yes, of course I was upset I missed the event but I had no choice unless I left in the middle of something else and that is just rude.  The person hosting the event I missed was not angry.  She totally understood and we made plans to meet up at a later date.  Yet my temper tantrum throwing adult is still immensely upset with me.  Sorry but I am not sorry.  Okay, I am sorry I missed the other event but I am not sorry that you missed it.  You could have gone without me.  Don't be mad at me because you chose not to drive someplace you were not 100% familiar with.  I do it all the time, grow up.  Print a map...or something.  I was being nice agreeing to rush from the other event to meet you someplace to pick you up so you wouldn't have to stress about driving but it is not my responsibility to make sure you have a ride when you are perfectly capable of driving yourself.    I had plans already...plans you knew about...plans that I said before hand may prevent me from making it to the other event and you chose to ignore me.

Being angry with me the day of is one thing but ignoring my calls and texts for DAYS is a whole other level.  If you cannot be an adult and speak to me and tell me you are upset I am not going to call you anymore.  I will wait until you are ready to be mature, I am not begging for forgiveness.  I apologized, I tried to call and apologize ...now I want an apology for having to deal with this BS but I am not going pursue it.  I refuse to be a part of your drama.  I have better things to do than stress about whether or not you are mad at me because of something so trivial. 

Does anyone else have this issue with an adult(s)?!?  Or am I the only one blessed with this type of person.