My family had a Russian exchange student from near Smolensk.
She had 2 years left of HS before University (She went to Belarus State)
When she came for 11th grade, she did NOT learn anything that she had learned in 9-10th grade in Russia. So the only thing she learned was better English skills.
In the USA, we have school for children from ages 5 to ages 18.
After that, they usually CAN goto a University, or try to learn a trade ( Electricity, welding, plumbing) or try to find a job, or live with their parents.