Even if colleges have adequate testing capacities, there are still going to be issues that come with reopening colleges. Firstly, the cost of testing is very high. For example, the University of Wisconsin expects to pay $20 million for each round of college-wide testing.
The chancellor of California State University, Timothy White, says that testing half of the college's student population each week will cost $25 million per week.
This high cost is too much to handle for many institutions, so remaining closed and moving everything online for now seems like the better option.