The projects are more individualized and also less likely to be copied. For example, one of our math teachers suspected a student was cheating in algebra when she noticed a big jump in test scores. Self-selected grading seems to work as well. In some courses, the student chooses the grade they wish to work for. If they want to fast track for a lower than A grade then they do less work instead of the same amount of work with less quality.
Some courses build repeated opportunities for success.
In using online self-paced courses, work that does not come up to expectation can be sent back to the student for improvement without delaying the rest of the class. Another strategy from our health and social studies courses is to incorporate a great deal of personal reflection, discussion, and application of the material. That sort of work is very hard to duplicate. The very nature of asynchronous distance education seems to lessen the incentive and opportunity to cheat compared to a traditional classroom. A student does not have a buddy across the aisle that didn't do the assignment and a deadline is upon them.