Seattle has one of the lowest market shares of any major city in the US. From the Seattle Weekly:
The school district estimates that only 68 percent of school-age children in Seattle attend public school. "If we were an average U.S. district," says schools Finance Director Steve Nielsen, "we would have 90 percent market share." Among big cities, he says, the average figure is around 80 percent. That leaves a share of poor students in Seattle's public system that is inconsistent with the actual demographics of one of America's most affluent cities.
A 2001 U.S. Census survey, sampling residents from big cities across the country, suggested that Seattle might have the largest rate of private school attendance in the country.
http://www.seattleweekly.com/2005-06-15/news/the-poverty-factor/
Market share may be aggravating many of our other issues with our Seattle Public Schools. High market share is critical to have community support for public schools, to be able to pass taxes that fund the public schools, and to maximize the involvement of parents in helping the schools.
The District's funding from state and federal sources is also directly tied to enrollment. If the District can enroll more students they will get greater revenue. While their variable costs will increase with additional enrollment, their fixed costs will not and therefore they will have more funding for things that aren't funded now. In addition, private school students typically have involved families who value education, so they bring more to the District than just the additional funding from the state and federal government.
While these are all good reasons for the District to work to increase enrollment and market share, there is a more fundamental issue. The District is not responsive to the needs of the community it serves, and this is the flaw at the root of many of the District's problems. The District should do a little work to find out why families make other education choices. Why do they choose private school or home school or another district? The District doesn't even think to ask. It would be another leap for them to take some action to address the perceived deficiency.
In some cases, it is a simple matter of capacity. Families living north of 85th often choose Shoreline schools because the Seattle schools are full. Families on Capitol Hill or in Eastlake choose private schools because their neighborhood schools are full. There are some families that want an alternative academic experience for their child but cannot gain access to our alternative schools because they are full. Real capacity management would address those problems and add enrollment in Seattle Public Schools.
In some cases, the reasons are programmatic. In Madrona, the neighborhood school has chosen not to address the needs of local families. In Southeast Seattle middle-class Black families don't trust the District to set and maintain high academic expectations for their children. Again, there are steps the District can take to address these problems.
In some cases it is simply a matter of security. There are families in all parts of the District who do not believe that the public school is safe for their child. The District must address this issue as well.
In all of these cases, however, the District cannot address the problems unless the District knows about it, cares about it, and wants to address it. I don't think any of those elements are currently in place. They would be in place if the District believed that it was their mission to be responsive to the needs of the community they serve.