That's not the same place.
Yes, they do have their own public schools, but that's ignoring how isolated and segregated those schools are that tax base is from the rest of the community.
In the 2015-2016 school year, HPISD had a student population of 7,171 people, of whom 2,114 were at Highland Park High School. The areas from which HPISD draws, Highland Park and University Park, have a reputation for being affluent, predominantly white areas. The numbers show that although the student body used to be almost 99% white, by 2015 a lower 86.5% of the District was white. The next biggest sections are a 6% Asian population and a 5% Hispanic population. In terms of affluence, it is true that 0.0% of the District's students are economically disadvantaged. The rate of violent or criminal incidents at every single campus in the District in 2015-2016 was 0.0%
Dobb's isn't that bad, but its demographics and income is still well above many nearby areas. Go through the Dobb's high site and count dark skinned people. It's an 80% majority community with a family income well over nearby areas.