There is a way for poor but talented kids to get into good schools, it's called scholarships.
Education is a very complicated issue and there are no easy solutions. There is no way to be fair to everyone. Whatever is done will always be a compromise. In HK, kids are streamed by ability so you get situations where you have kids of similar abilities in the same school. That's a fabulous scheme for the ones that are talented but putting all the weaker kids together is simply setting them up for failure and makes trying to create a healthy teaching environment incredibly challenging. Most studies have determined that in groups that are more diverse, the lower kids have a better chance of success however that only works when there's enough diversity. In many public schools around the world, parents that have money will generally send their kids to private schools therefore avoiding that diversity and creating a hole that can never be filled.
As a parent, I wouldn't hesitate one second in trying to get my child in the best educational environment possible. However, when looking at society in general, I believe that we would benefit more from less segregation. The talented and the gifted are more likely to thrive regardless of the environment but it's the complete opposite for kids at the other end of the spectrum. However asking parents to be selfless and act for the benefit of others instead of their own children is completely unrealistic so we are left with a mish mash of attempts to somehow placate every group but never really committing to a course of action.