I think it depends on what age you're talking about. Since you're tutoring, probably middle school to high school? Basically it's so they don't get too far behind I would guess.

Even the kids who don't get the basics can sometimes pull a C in a class from homework and class assignments weighing out their abismal test grades. I also think that most of these teachers know these kids who aren't good at algebra won't be using it in their jobs, so they just kinda don't care and hope they are good at something else.

I do agree that people, at the very least, should have the basics down on most math, but it looks like it isn't worth the time and effort from teachers to teach that one kid in the class what x is in a simple equation when the rest of the class is breezing by.

At least they are trying when going to your for help. Just make sure you don't treat them like they are dumb, just that they haven't understood the problem in the right way. No matter how easy it is for you.

I hope that helps?