God @blueshoes, the contempt dripping off you. You really do revel in bringing the stereotype to life don't you?
If you were to look abroad as a result of progressive changes in education policy, I daresay the country would survive it. AFAIC, it isn't about bringing in astonishingly gifted parents like yourself to state PTAs who will save the failing institution from itself 
. It's about removing a parallel system that poaches the best teachers. And no I don't blame the teachers. They went into teaching because they want to teach; this is much easier to do well at a private than at a state school (in general, I hasten to add, before all the fantastic state school/shit private school examples start again).
Add a massive salary increase and private company benefits and frankly you'd have to be saintly to resist (some teachers are saintly, mind, and stay in state schools because they believe - rightly in my opinion - that the impact they can have there will be of far higher value even though it will be harder to achieve. Like NHS doctors who could be working privately but choose on principle not to, these people are my heroes).
As I said below, I don't expect individuals to be saints and Do The Right Thing, off their own back, to their own detriment, in their daily lives. We, as a species, in aggregate, are not that good. But we know that the right thing to do is make sure everyone has 'good enough' before we have 'best' (or most of us do). So while it isn't fair to expect an individual teacher with their own wants to think about to turn down a job at a private school, it is not unreasonable to expect people to vote for a government that takes away that temptation.
Cherry, comparing the education system to a fancy car is just crass beyond all measure. Unless of course you think state education should be scrapped altogether and people can only learn to read and write and reason to the extent that they can afford to pay for it? Or to reverse it, that the government should be providing everyone with a basic banger which you can then pay to upgrade should you so choose?
Education is like healthcare. A social good, an essential, fundamental part of what makes society society, rather than just a cluster of humans living alongside each other and scrapping for what they can get. Knowledge and curiosity are partof what make life worth living. Would you say cancer treatment (or indeed any medical care beyond being basically patched up in A&E) is a luxury product, for those who can afford it, like an SUV? I say this incredulously but thinking about it you may very well think it is.