Sharing encrypted data is quite complex. We have now achieved a milestone by enabling you to share your zero-knowledge calendar with others! 😃🎉 https://tutanota.com/blog/posts/release-notes-calendar-share
@GLove Thanks for your feedback. Developing the encrypted calendar takes a lot of development time that so far has been given to everyone for free. It's like a separate app - when it comes to development effort. As such, there must be a way to monetize the calendar. We'd have loved to include it in Premium, but for this the Premium price is too low. If you consider it like this: €2 for Premium plus sharing isn't too much.
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!