I tutored math in college. I agree with this author.
Most people will struggle with Calculus even if they are very bright. It takes a certain level of maturity to handle it and a good ability to solve problems methodically. It also takes a thorough grounding in Algebra and Trig. I always started with teaching how to solve problems using a method, then went into the nuts and bolts. I've seen D students make A's and I've seen a lot of others continue to fail.
The answer to the issue is threefold.
1. A lot of people do not belong in a technical field of study at the collegiate level. They need other technical outlets that are not primarily intellectual.
2. Many teachers are not up to the task. Most retired engineers can teach math with their eyes closed, but no amount of instruction will make most teachers' college grads able to teach it.
3. Kids should be grouped by ability based upon standardized tests. This way material can be presented in a way that is appropriate.
The fact of 1-3 means the good teachers ability to impact the right students is diluted by pushing too many kids on the wrong study track. And then most students do not get the right exposure at the right time.
