New
#1
Most of the online storage solutions that I've seen only store one copy of a file. Thousands of users might be paying to store the same file, but only one copy (not counting the vendor's backup copies) is stored in the cloud. To do that, the vendor must know/use the encryption key.
It is fine to say that it would be more secure if each user had/used a unique key, but each user might end up paying more.