YES! I was a a coffee meeting with teachers when SD was in 5th grade. This was when bluetooths came on the scene. The guy next to me was laughing at weird times. I realized he was listening to someone on his bluetooth, and not the presentation for the parents. This was important stuff! Middle school and growing up and how to help your kid! I was stunned that he would take the time to be there but not BE there.
Or, more recently, SD was sitting next to a couple who were surfing the internet on their phones and not paying a smidge of attention to Sir Terry Pratchett and she was stunned. She said, "They PAID to be here! What was so interesting that they couldn't pay attention for an hour to SIR TERRY PRATCHETT!" It was just rude.
If you are doing a job (watching kids on a trip) then you do the job or don't bother to volunteer.
I also agree that if you can't put down the phone (which now includes a small computer), then you will miss so much. Anybody see Hook? I applauded the wife when she threw his phone out the window. She was angry that his kids were growing up and he was missing it.
At our dinner table, there is nothing more important than the meal/family time. Phones OFF. No texting under the table. No phones buzzing on the sidelines to be glanced at. It's our time and we can spare 30-40 minutes a day for each other.
I think if the mom had a work situation and needed to be on the phone then she should not have been at the field trip. She was not doing what she signed up to do.