The highest point in Florida is 345 feet above sea level, so they don’t practice much in the way of mountain flying. They may never even need to lean the mixture at higher altitude.
However, it is a relatively inexpensive place to fly since the weather is pretty nice year round due to warm weather, despite the occasional rain and hurricanes.
This does not mean that the woman didn’t have plenty of training and experience in Italy, especially as she’d flown this route several times before.
The comment in avionics’s post is correct. You should be at least 2,000 feet above a mountain pass at high altitude, as a strong downdraft can make that margin disappear quickly.
Flying at high altitudes is akin to being a glider pilot. You need to pay attention to which way the wind blows and where there will be downdrafts versus updrafts, and plan your path with this in mind.