Another thing about Labor Day is that it is a holiday that most people get off from work. Not retail workers, or restaurant staff, or health care workers or staff at amusement parks and the like. But the average office/factory worker will get the day off.
But the US does not have any holidays where an employer is *required* to give employees the day off. Many employers follow the Federal Government's holiday schedule, which has ten holidays per year:
New Year's Day
Birthday of Martin Luther King, Jr.
But many do not. But the majority of people do get Memorial Day and Labor Day off, giving us two three-day weekends to bookend the summer season.
In addition, most people get New Year's Day, Independence Day (July 4th), Thanksgiving and Christmas Day off. But Martin Luther King, Jr. Day, Presidents Day, Columbus Day, and Veterans Day are really done on an employer by employer basis.
And since most of us get less vacation time off than people in Europe, we value each and every holiday.