I live in South Central PA here and they now start the school year mid August. It was August 17 this past school year. They are supposed to get out May 30. They never had Spring break even when they started a week later. It was always Good Friday and Easter Monday. My half-brother lives in Australia where their schools operate all through the year as you have described. Their biggest problem is what to do with the kids during the 2 weeks they are off every bunch of months. In this country it would be a mess because many businesses are based off the school schedule as it is. Just my opinion.I homeschool, so the schedule doesn't affect me at all. Our new school year always starts on July 1 and we do 180 days per the requirement, but we generally always do more.
I have a feeling we are fairly close to one another - I'm about 10 miles due south of Hanover, PA.
I totally get the mess that year round schooling would cause when it is first implemented, as with any large change to culture. Every new educational study that comes out finds that brain development and education is seriously hindered by any more than 15-20 days break in learning. But after a quarter century working in public education, I know all too well that the main focus is rarely on what would be best for actual learning!