Etiquette

I sent a handful of texts to several friends at a time. Me and girl friend summoned a reunion dinner and I was tasked to request the confirmation of presence to this gathering. Only sole of them reciprocated my text and confirmed to join the dinner, the rest of those I've texted didn't ring me up either. The sms was sent 2 days before the agreed day, hence I made some phone calls to those of whom haven't shown up.

The conversation went as follows :
Me : Hello, how are you!
Her : Hi, it's you! Hehee.. I'm doing fine! Anything I can do?
Me : Oor, just wondering whether u got my text?
Her : Oya, I got it.
Me : (trying to act witty) Then?? Why didn't u bother to reply me???
Her : Because I dont want to join! So, I dun think tat I need to squander my bucks on the sms fee!
Me : (getting puzzled with her rapid answer) ......................

I dun expect this kind of reply! Well, let me jot down wat I typed on my sms to her.
"Hi, guys! We are planning to summon you all for a reunion dinner on this coming Thursday. Kindly confirm your attendance. Place and time will be informed later. Thanks."

For me, I need to reply this text no matter I'm going or not. Tis is called ETIQUETTE.
Honestly I was in wrath after hearing her rude answer, but yet I have to act witty (again) to swerve the conversation into other topic. She might fib to make me better. At least she might said tat she was in the middle of doing something when I texted her and actually getting it forgotten.
What a lovely pretext, I will surely trust her!

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Another call to the other girl friend on the next day :
Me : Hi, our friend xxxx is getting married on the next Wednesday. And she invited you to join the banquet. She has limited time to distribute all the invitations, hence your invitation is with me. Feel free to come and collect from me if you have time.
Her : Oor, thanks! But I wont be going. I cant make it as I'll be very hectic on that day.
Me : I see. Ok then. I'll relay to the bride. ;)
And the phone line was disconnected.
Hahahaa.. Very funny! Why doesnt she consider to pack a red packet for the bride??

Tis is also considered as an etiquette breach? Or is she adopting this kind of nonchalant?