Yes - I've seen studies that show things like "quality education" don't really hold up under close inspection (for eg. when you control for student performance before college difference between elite colleges and standard ones disappears).

I would be interested how research defines this "high quality social/cultural environments" and how it controls for factors such as genetics, family cultural and financial background, etc. Separated twin studies would probably be ideal (but I'm not an expert in the field).

I agree; I'd like to see some long-term information on this.

I need proof when someone says "growing body of research".

It's not readily apparent that increasing the amount of children per staff member will significantly impact a child's ability to "succeed" in life as an adult.

I'm not sure how we expect a 1:6 ratio to be "cheap", even before factoring in costs like real estate.

For Head Start the staffing has a safety component. Think how many staff needed to get various ages out of a burning building.

Seems like a pretty weak reason to keep permanent staff unless fires are common. It's as if there is absolutely no-one else around who could help in an emergency except people paid to be there full time.

Telling a parent their kid burnt up because you didn't have the staff is not a weak reason. Safety is a component of staffing guidelines and not the only reason.