Why are events tied to only one calendar?

I need to be able to have multiple calendars views of the same event. A yearly calendar showing all my events. A yearly calendar showing only events of a certain category(color?). A monthly calendar of the same as the yearly types. A next event calendar showing only the very next event coming up (for my home page).

I don’t want to have to duplicate a single event five times to do this. Events are singular. Calendars should be multiple. I should be able to associate an event with any number of calendars. i.e. a many-to-many relationship is DB speak.