1. As someone mentioned: way more meets in high school. For sprinters, the meets themselves are a critical part of training.
2. Along with that: for most, the high school season goes 4-6 weeks later into the spring/summer than the college season does. Better weather, more races...
3. Many college sprint coaches do not seem to understand that, for most sprinters, base training should focus above all on the development of top speed. Why? Because, for virtually any sprinter, what is "basic" for that athlete is running at high speed for brief periods--duh, that's what a sprinter is!
Charlie Francis had a clue on this--it's sad that so many college coaches don't. Overdistance should *not* be a major part of most sprinters' base training--it drains their adaptation reserves, early in the training cycle. Instead they should be doing a mix of activities (running and other), like the all-round fast-twitch athletes they generally are. One of those activities should be gradual development/improvement of top speed. For in-shape athletes, this should include overspeed: things like flying sprints with the wind at your back, towing, and sprinting down very, very slight inclines.
Good high school sprinters typically do football in the fall, and often basketball in the winter. Those are activities much more likely to get them ready for springtime sprinting, compared to the so-called "correct" training that has a sprinter doing cross-country in the fall and continued overdistance in the winter. Those things just slow a sprinter down.
And, yeah, the drinking, late nights, and sleep deprivation in college don't help.