I can't find a way to tell the Atlassian markup engine to ignore formatting code within an inline portion of text. For example if I write [_var_ for _var_(*args) in list] in a Crucible comment, it thinks this is a link with underlines etc.
I'm not interested in escaping (with \) each individual markup character in this block of code; it's error prone and messy. The {noformat} macro creates a block of text (separate paragraph), not inline with surrounding text.
I've searched at length, and the closest I've found is an SO answer by creating a custom macro. This might work but I don't have admin access to our JIRA, and it seems like this macro would have to be created for all of our Atlassian services (JIRA, Crucible, FishEye, etc).
Is there no other way to do this simple and basic operation of escaping an inline portion of text from the markup engine?
What you are asking for is perfectly reasonable. Sadly, that is not currently a feature of the Atlassian comment editor. The only way to achieve in-line escaping currently is to use the backslash before each special character.
A custom macro, deployed as an atlassian add-on, would give you what you need. You could develop an add-on yourself, using the Atlassian Software Development Kit (SDK).
Alternatively, AppFusions could develop the add-on for you, on a commercial basis. I think you might find that option cost-effective.