Perhaps some of this is just young age and naivete plus that sense of immortality that starts to go away around age 30?
I did an inexpensive backpacking trip around Europe at college graduation time. It took really bizarre stuff to get me worried. I hopped off the train in each town and started looking for an inexpensive place to stay. I also did not understand why my parents were so worried and I was annoyed that they wanted me to call them frequently. This was of course before handheld phones existed. Overseas calls were a hassle and expense from a payphone.
I might make the same trip today, but I would have a lot more regard for each direction I went, a lot more awareness of my surroundings, and a plan of what to do if attacked. I was really pretty helpless and lucky. It's not that I went anywhere terribly dangerous, but it was very obvious that I was a tourist who didn't know where I was going nor have anyone to help me.
Kinda reminds me of the Mike Tyson quote, "Everybody has a plan until they get punched in the mouth."
It's a failure of imagination; it's hard to imagine with accuracy what we've never experienced. We have to experience a few things to overcome the exuberance in coming of age. Maybe by age 30 most of us have at least learned enough to fill in an outline of what we don't know, that we become more cautious. I tell my son to experience as much as he can as early in life as he can, because we don't learn how to face life just by waking up each morning. We have to experience the day of hardships and working out solutions to problems. The more we experience each day, the sooner we learn the lessons. Your backpacking trip probably taught you a lot.
IndyMike's gf was shocked because she had an inaccurate imagination. But now having that experience she likely views her own abilities with at least a little more accuracy.