You have these options as an admin when using GSuite:

> No sharing — Calendars aren't shared unless users share their own calendars. Note: If you choose No sharing, your mobile app users can't use the Find a time feature. > Only free/busy information (hide event details)—Only free/busy information displays. >Share all information — All information is public unless users change their own settings. Users can also make individual events private.

Then you can manually override these settings as a user.

This is just a default setting, though. Often it's useful to know what meetings are occurring so you can attend or contribute info, and it's certainly useful to know who's booked a room so you can swap or shift them to video conference if you need the room more.

Because Google is heavily employee-driven and trusts individual employees to determine what's relevant to solving the problems at hand.

My teammates calendar topics are visible to me so that I can notice if they're getting pulled into meetings on topics that I should be meeting with them also. My boss's calendar topics are visible to me so that I'm empowered to ballpark the relevance of my project in context of other things my boss is managing (and so I can notice if my boss is working on something that should be relevant to my project that nobody has noticed is relevant yet).