^^This is the key^^^
Think of how many Faiths that observe Christmas there are in the world, then figure how many actually observe the holiday, and then it becomes clear
During the 20th century prior to 1990, the popularity of Christianity had been stable in the U.S. About 87% of adults identified themselves as Christians. The country then experienced a major change. Significant numbers of American adults began to disaffiliate themselves from Christianity and from other organized religions. By 2008, the percentage of Christians had reached 76% and is believed to be continuing its decline.
Religious identification in the U.S.
In addition to detailing the current religious makeup of the U.S. and describing the dynamic changes in religious affiliation, the findings from the Landscape Survey also provide important clues about the future direction of religious affiliation in the U.S. By detailing the age distribution of different religious groups, for instance, the study's statistics on religion show that more than six-in-ten Americans age 70 and older (62%) are Protestant but that this number is only about four-in-ten (43%) among Americans ages 18-29. Conversely, young adults ages 18-29 are much more likely than those age 70 and older to say that they are not affiliated with any particular religion (25% vs. 8%). If these generational patterns persist, recent declines in the number of Protestants and growth in the size of the unaffiliated population may continue.
Statistics on Religion in America Report -- Pew Forum on Religion & Public Life
In short, what Micky D's is noticing is that there are a lot of people who do not observe Christmas.
My wife is working her afternoon shift @ the hospital Christmas day.