Just wondering again....
How might the product have been designed?
For jobs it might be beneficial to know if the job ran, when it ran, completed successfully etc. as jobs typically modify the data in the system.
Reports on the other hand do not modify the data.
They are typically run either immediately so the user who ran the report know if the report ran or not (either he or she gets the report displayed or not). The same could apply to the shared resources,too.
Or the report is run scheduled in which case the user who scheduled it and the users who were shared to the report would see that in the report in library after it has been run or at least a record for it.
So I think the product is working as designed when the Enable log box is not there for the reports.
Why might you want to log reports?
Are you after who ran this report? There have been discussion threads about that..