Why are the following fields missing when I'm trying to add a field to the request types page?

[JConstantine]

Here are fields for the "Support" issue type:
When I'm editing the request types in Service Desk and trying to add a field I don't see the fields from the screenshot up above (marked red).
Why is that so?

[Nic Brough -Adaptavist-]

The fields you have in red are not to be set by the customer, so there's no point putting them on the request screen.