I'm sad to say that your experience with PTO is not the norm in the US. The lower and most of the middle classes have it much worse: http://theweek.com/articles/463897/americas-war-vacation-by-...
Most people only get 5 weeks of holiday a year total (4 weeks is the legal minimum) and they usually spread out those days over the year. If you can travel the world for 6 weeks every summer then you have an above-average number of free days and probably an above-average income to be able to afford that much travel.
We do get vacation money (8% of your gross salary, usually paid in may) but that's not nearly enough for 6 weeks of travel unless you saved up a lot.
You say people "only" get 5 weeks of holiday, but that only supports my main point about the huge difference between that and what Americans are used to.