We sort kids into the smart and non-smart labels when they are young, and those labels tend to stick, even when what we're measuring isn't raw intelligence but just variance in childhood development that wash out in the long term. I don't think either group is well served by this.
No we don't. Public schools are incentivized not to help high performers. It actually hurts their metrics and budget. The widespread gifted/talented experience in public school ended in the late 90s.
The actual intelligence segregation is self-selected. PMC parents live together in the same neighborhoods. Whether you believe in genetic or social factors, the smart kids come from here.
In the 80s and 90s there was an educational culture that believed in finding overlooked geniuses regardless of where they are from. That narrative is completely dead. All institutions expect kids to come prepared with a resume from their youth, and have few avenues for identifying talent that doesn't meet their mold.
A smart kid can be anything from not eating rocks anymore to multiplying numbers at an early age.
Most of us turn out like the rescued exotic bird which turns out to be a seagull covered in curry.