Guests can: Modify event
In Google Calendar it is possible to grant specific Rights to the invited people.
(Modify event, Invite others, See guest list)
The one that I miss most is the right to modify the Event.
Why I need it:
If the invited person edits for example the notes for the meeting or adds address, then without this permission it will by applied only to their separate copy of the meeting. In many meetings it is much better if the Attendees can collaborate add notes, specify address, shift time.
It is of course possible to grant such right en bloc for the whole shared calendar, but then it brings the risk that the other person may accidentally modify or delete all other meetings. Having the possibility to grant the right only to meetings where collaboration is wanted and to persons participating in the meeting - that would be much better.