I think that the USA is one of the countries with the most opportunities to get a bitcoin quickly, 257 hours of work, it may be somewhat exaggerated, however it is a statistic.
You need to factor competitions too. Having a high standard pay-rate means nothing if you can't even get a job.
I am not an American but if you are an American and do tasks/ offers or ptc to earn Bitcoin, then you will earn much faster than others because they often offer a high earning rate for American.
They also have a higher standard of living. Put it simply, making $5/hour and get a $200/month job is good enough in my city. So good that you can still buy useless things every month and then without worrying about what you should eat next week.