Is it that common? How do they handle backpackers?
I've literally never gone on a single multi-week vacation in my entire life with fully booked accommodation for the whole thing. I book the majority of the first week and I know when I'm flying back, but in between I'm mostly guided by the wind.
I can't book hotels in places I don't know I'll be going.
Double income, single household, no kids. (and even then just barely, i will add)
Or, if you're talking time wise, live in a country that isn't run by and for corporations and you can still enjoy some paid time off.