Joseph…..
No, one would not ask for the potential machatenester’s HS Diploma. You might ask the potential SIL/DIL where did your parents graduate?
Should the potential SIL/DIL have to dance around and reply: mom attended XYZ High School, as opposed to a truthful ‘mom didn’t graduate high school.’
May not seem important yo you, but mothers often help children with homework and I would want the mother of my grandchildren to be able to help with work though high school.
In our family’s case it is doubtful that our children/grandchildren would even have a first meeting with a potential mate whose parents did not have advanced degrees, never mind college and high school; but us being professionals who are part of the Hareidi world is not the norm.