It is likely that as we get older, we get a little more aware of the ways of life, our life, that of others and the ways of the biological and physical world. I thought that older people became aware of their body changes and greater limitations and that greater awareness caused greater caution and inclination to stay home and "safe". That idea may well be somewhat applicable but I can see a different process possibly at work as well.
Especially for those who regularly practice increased mindfulness, it seems possible to be more aware of the entire process of travel. We were just listing them together the other day. As older people, we are constantly made aware by doctors and the media that our hearts, lungs, kidneys, skin, liver and other parts may fail or develop difficulties. So, we can picture the miracles of the body processes and it is easy to get my brother-in-law's feeling that with all that complexity, something is going to go awry. And that is just the internal processes of the body.
Getting a car ride to the airport, having the plane we need successfully land, taxi up without crashing into the extending walkway we will use to enter the plane, fitting our luggage into the overhead bin without spraining or straining: it isn't that we think that is going to happen. It is just that we don't expect all those events and many, many more to go as planned and not fail, at least partly. If we were little kids or blithely unaware of system and component failures, we might whistle happily through the beginning, middle and end of our trip. But we are nearly the human opposite of little kids and we are astounded that our trips have gone so well.
So, here's to the Irish cliffs of Moher and the Scottish Highlands!