tl;dr
Sometimes staff don't like to be woken up at home.
Example:
Go to Support > Staff > Edit (one of the staff users).
Notice that there are several checkboxes representing different ticket priorities you can select (e.g. "Emergency", "Critical", etc.)
Some Staff may want to receive all of those ticket notifications to their work email at their work computer when they're at work. However, when they're at home sleeping, they may not want their phone to wake them up because of a ticket notification unless it is an "Emergency" ticket that they need to deal with. That page allows them to configure the ticket notice emails they will receive.
The Order email is similar, but you configure your settings for that under Billing > Overview > (click the settings/gear icon at the top right of the Orders widget).