What a shame they couldn’t come.
What a shame they can’t come.
Is there any difference between them?
The only difference is couldn't(past) vs. can't(present).
In other words, 'couldn't' means past here?
What a shame they couldn’t come.
What a shame they can’t come.
Is there any difference between them?
The only difference is couldn't(past) vs. can't(present).
In other words, 'couldn't' means past here?
In other words, 'couldn't' means past here?
Yes
What a shame they couldn’t come. = What a shame [that at the time I asked them] they were unable to come.
or (said after the event has happened) = What a shame they were unable to come [to the event that has now ended/took place in the past].
What a shame they can’t come. = What a shame that [currently] they are unable to come.