The US doesn't mandate any vacation or sick leave days, so a huge chunk of the population can't even get a week off work, much less afford $4k per person.
I would imagine the set of people who would spend $4K per person on a week in the Galapagos does not contain very many people who don’t have 3 weeks of vacation per year (or are retired).
I would imagine the set of people who would spend $4K per person on a week in the Galapagos does not contain very many people who don’t have 3 weeks of vacation per year (or are retired).