The situation used to be that students who could not pass math or English were flunked, often several times, until the dropped out. Now the tendency is to pass them and keep them in school.In one Miami Dade High School where I taught for about three months in 1987 as a permanent substitute, we were told that you should not fail over 6% of the class, so if you had 30 students, you could fail only two. To flunk more than that, you needed to submit an "override form", explaining in detail why they failed, what measures should be taken so that they could pass when the retook the class, and then you had to get a parent or guardian to sign off on it. It was said that if you had too many overrides, you would not be rehired. I never met anyone,and no one could name anyone, who had been non-renewed for excess overrides, though.
I imagine that something similar is used to hurry the students through the system elsewhere. I had at least a dozen students in my six classes that could not or would not read aloud. When they tried, they sounded like second graders, mumbling and stammering along.
I reported their difficulty to the remedial studies office, where some teachers were already familiar with most of them.
I decided that I did not want to teach HS, even though it paid about 25% more. This was one summer when my college decided to limit summer courses because of remodeling being done to the classrooms.
It is difficult trying to teach students who lack the basic skills in a high school. Miami has a lot of Haitians, Cubans, Central Americans who know no English and some of whom cannot read in their own language. They come here when they are HS age and there is no real place to put them after a crash course in ESL that is inadequate.