That would require the VPN service to keep track of users’ usage and be able to match traffic to user, which most (or most of the big ones at least) very specifically, very on purpose, explicitly say they don’t do, which would be really bad for them if it turned out to be false.
You can never truly know about almost any online service, you kinda just have to take their word for it, do some research, and pick the option that best matches both the performance and philosophy you’re looking for.