In its order, now overturned by @GovLarryHogan, Montgomery County had forbidden private and religious schools to offer in-person instruction before Oct. 1. I'd been puzzled about why it had selected this particular date -- did it reflect some sort of public health timing? /1
Then someone pointed out that Sept. 30 is the cutoff date in Maryland to count official public school enrollment. Many real-world consequences, including the magnitude of state and federal grants, depend on the count as of a census date like that. /2 http://marylandpublicschools.org/about/Documents/OCP/Publications/MDStudentRecordsSystemManual2016.pdf
Note also that MCPS's superintendent acknowledged July 22 that the system's enrollment of new students was coming in well below expectations -- only about 300 K-12 new students instead of the expected 2,500. /3 https://www.mymcmedia.org/smith-says-he-understands-families-choices-as-mcps-enrollment-is-below-projection/
The safety issues here are complex and I don't know what the right answers are, or whether there is exactly one such answer right for all kids and schools. /4 https://www.washingtonexaminer.com/opinion/private-schools-were-taking-extensive-coronavirus-precautions-maryland-bureaucrats-didnt-care
Still, I can see why there's a problem in leaving an arbitrary power to shut down private and religious schools in the hands of their biggest competitor. /5