I've been to Prospect Cemetery several times to find family. They do have the original books on file that list each person buried there. The books include the person's age, cause of death, next of kin, undertaker, etc.
I haven't been there in at least 10 years. But I know of 2 other large cemeteries in Toronto that are not allowing the public (including family members) to view their records anymore. Supposidely it has something to do with a new privacy law. I don't know if the cemetery has chosen to adopt these new laws or what. I never had a problem obtaining the books for my research but suddenly it's become an issue.
The cemetery would know how many people are buried in that plot by checking their cards.