This is an area full of patents that created a picket fence (or mine field) where this feature you found in apps I won't mention from MSFT meant that it may be years before you see this in Google Calendar.
So with the patent issue out of the way you know why it's not happening. Also some rail against the complexity (What do you mean I have to mark the event Public?)?
Bob
We have a small group and would like to be able to coordinate our calendars using only our phones, is there an app that will allow us to sync our calendars with each other? We have looked at Google Calendars but it doesn't sync events made on your phone calendar with the shared calendar. We are looking for something really simple that if I add an event on my phone everyone else can see that event.
Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic