Summer plans also do not need to include fancy or expensive programs. Regarding summer enrichment programs (like summer programs at universities), opinions seem to be mixed because some people think it is a waste of time, especially for American students, because for American students it may not help with their application for admission, but for Chinese students it may help to give them a better idea of what US university classes are like and the potential for building credibility on their application. If the summer enrichment program is focused on a specific area such as journalism or robotics that the student is genuinely interested in, then it becomes a good reason to participate. However, if a Chinese student is accepted to a selective summer enrichment program at a university and is interested in going, I would still suggest that they do not only take classes while they are in the program--just like with SAT classes, I would recommend that the student spend time outside of classes and doing coursework to pursue other interests nearby, continue to reflect, try to volunteer or do an internship nearby, etc. 

Harvard is actually very worried about the mental health of students and say that "Families should allow for “down-time” during vacations, weekends, and during the week at mealtimes or at any other break..Summer need not be totally consumed by highly structured programs, such as summer schools, travel programs, or athletic camps. While such activities can be wonderful in many ways, they can also add to stress by assembling “super peers” who set nearly     impossible standards. Activities in which one can develop at one’s own pace can be much more pleasant and helpful. An old-fashioned summer job that provides a contrast to the school year or allows students to meet others of differing backgrounds, ages, and life experiences is often invaluable in providing psychological downtime and a window on future possibilities. Students need ample free time to reflect, to recreate (i.e. to “re-create” themselves without the driving pressure to achieve as an influence), and to gather strength for the school year ahead." They say that students who have always been told to do one stressful program after another with no genuine interest very quickly burn out or have mental breakdowns once they reach college, and then may be forced to take a year off. Here is where they say this:

https://college.harvard.edu/admissions/preparing-college/should-i-take-time

In conclusion, US students do use their summers to add impressive things on their high school resumes, but they also try to schedule time to pursue activities that will help guide them to making more meaningful personal decisions about what to pursue, and sometimes that means pursuing activities to know themselves better first, and to challenge themselves in ways that make them uncomfortable, so that they can grow.