" The US system (school funding from local property tax) then adds a second advantage to those same children, rather than even attempting to redress the balance for the disadvantaged kids."
Sadly you are correct. It does give children of affluent families a (theoretical at least) advantage.
The problem is what to do about it. Putting aside for a moment the very rich, what do you say to those people that have worked hard to buy a home in a neighborhood with good schools? If school funding is somehow leveled out what happens to the value of those homes, now that it is no longer seen as being in a "good" school district relative to other neighborhoods?
Rich people can always send their kids to private schools and hire tutors and give their kids advantages that the rest of us don't have. Nothing we can do about that.
What about the upper middle class family making, say, $200K a year? They worked hard and made sacrifices to buy a 500K home in a good neighborhood so that their kids can go to one of the best schools. Is it fair to punish them by raising their taxes or reducing the funding to their schools?
These sorts of things always start out as "punish the rich" and end up being "punish the middle class" because the rich can always find a way around these things.
At the risk of sounding harsh, perhaps *some* disadvantaged people should be taking a look in the mirror. Maybe, just maybe, they play a part in their current circumstances. Of course there are some people that find themselves in a tough spot through no fault of their own. Society should, and must, take care of those people.
But there are some - maybe many - that are there because they made bad choices. Some of them are the kids at the back of the class in high school - goofing off and not doing their homework and generally not giving a shit. Didn't go to college. No skills. Drunk. High.
Sorry but I don't feel much an obligation to support these types of people. If people are lazy then no amount of handouts is going to help in the long term.