Here's my story: when I was a tween, I went to summer camp which offered short 3 day overnight trips outside the state. I had a designated day and time to call my parents, which I did do to check in. Well, wouldn't you know, I got seriously injured along with three other campers on a broken mountain slide in NH. After getting us medical attention (this took several hours in which the entire camp (50 kids?) pretty much sat in the parking lot of the hospital), then taking us to get something to eat (we were banged up pretty bad but all of us were treated as outpatients), I had to call my parents again to let them know what happened. My mother picked up and immediately said "what happened"? She knew something was wrong because I wasn't supposed to call again.
Long story short, for the most part we all recovered and it has NOT stopped me from sending my daughter off to resident camp at the tender age of 9 years old (I was a little older) and on school overnight trips.
I agree that kids should check in when the arrive at their destination. But I think your issue has more to do with the differences in parenting style and worry levels that you have with the ex.
Mark Twain said toward the end of his life, "I'm an old man, and I've had many troubles-most of which never happened!"