Omission of ‘that’ leading an extra-posed subjective clause

Hello, everyone,

“Is it any wonder we love automation? By offering to reduce the amount of work we have to do, by promising to fill our lives with greater ease, comfort, and convenience, computers and other labor-saving technologies appeal to our eager but misguided desire for release from what we perceive as toil.“

*source;

https://books.google.co.kr/books?id=GhV0AwAAQBAJ&pg=PT16&lpg=PT16&dq=%22By+offering+to+reduce+the+amount+of+work+we+have+to+do%22&source=bl&ots=fQ4Sm0OWcM&sig=ACfU3U3GWKQ-EZREijaWPTq9qYf7Ivajyw&hl=ko&sa=X&ved=2ahUKEwjE4vHV2Lr1AhXpslYBHWoYBesQ6AF6BAgCEAM#v=onepage&q=%22By%20offering%20to%20reduce%20the%20amount%20of%20work%20we%20have%20to%20do%22&f=false

I’d like to know which word among ‘that’ and ‘why’ has been left out between ‘any wonder’ and ‘we’ in the first sentence above. I assume ‘that’ (leading an extra-posed subjective clause) has been done, since I’ve found one relevant explanation below from a well known grammar web, which might justify my choice, even though ‘any wonder’ is a short nominal predicative complement;

Quote

“Generally, it depends on the structure of the matrix clause and the content clause itself. In matrix clauses containing "be" + a short predicative complement, like those in your examples, I'd say that "that" can be omitted, especially in informal style;

• It's good they're on your side.
• It's possible she wrote it.

But compare:

• It distresses me [that he is trying to lay the blame for the accident on us].
• It disturbs her [that he was acquitted].

In these examples, the omission of "that" is very unlikely.

Unquote

Will appreciate, if you kindly provide me valuable opinions.