My friendship group had this problem, with lots of different messages flying around. We all work and lost of us have children - so all busy.
However, to get round the issue of numerous groups - WhatsApp, FB, text etc. as a group of friends we decided to set up one FB group for all arrangement/plans for lunches, meet ups, drinks etc. We all just use that one group. However, one friend in particular never responds to anything, but used to expect us to follow up with a phone call specifically to her. She used to expect me to phone her to tell her what plans had been out in the group chat rather than just reading and responding. We have had this group for about 5 years now and she is always too busy/stressed to read and respond.
It got to a stage where I told her I was stopping being her ‘social secretary’ as I was too busy and it was actually causing me stress. I told her it was now her responsibility to read the messages and do her own responses.
I have lost count of the amount of social events that she has now missed, but that is her choice.
OP, if you didn’t respond to me, confirming a meet up (which would take about 20 seconds to type ‘yes’) then I would assume you weren’t coming. It’s not other people’s jobs to chase you up by phone - people have busy lives and can’t be chasing round after people who can’t be bothered to respond to a simple message.