Well I think it is because it is seen as a divisive act, and [killing for MN] it is perceived as arrogant, superior and the assumption is that if you go private your SOLE reason for doing so is that you don't want to send your child to school with THEIR child.
This gets peoples backs up, rightly so, even though the thinking is crude.
There are huge wide-sweeping assumptions made on all sides - sometimes fuelled by personal experience but usually fuelled by insecurity and touchiness about one's life and ones children.
It would be difficult for the majority to endorse what a minority do. Because it isn't open to the majority, and therefore has to be seen as a badthing because that makes it bearable.
Then add into the mix people who object on moral grounds, people who love their schools and genuinely think the private going ones are fools, people who are outraged at the injustice that those with money have a better or easier life.
Then you get to question whether their life IS actually better, because poster A knows a child who goes private and was horribly bullied because they had the wrong trainers, and poster A knows that child would not have been bullied at her child's very inclusive state school. Poster B doesn't think the child would have been bullied at her private school either, in fact Poster B has never heard of such a thing, and wonders what this private school must be like because she's never heard of such a thing in all her born days. Poster C says that actually they are seriously mean at her child's state secondary school about clothes, she says it is part of the message they give off, and she knows parents with nothing who save up money for their children to have the right trainers. Poster D thinks they must be right idiots then and she would NEVER do that. Oh and she does send hers private too which causes Poster A to remark that she probably has never had to save up for trainers then, has she? And Poster D has to admit that actually no, she hasn't ever had to but wouldn't buy smart ones anyway because they only get ruined and her ds doesn't care and still wears ones from Clarks. Then Poster E says she thought this was supposed to be a thread about education, not trainers.