In English, the "shame"has the following meaning
a condition of humiliating disgrace or disrepute
However, it's common to hear people say something like
(1) It's a shame we can't take them home with us.
(2) It's a shame that you haven't read this book.
In such situations, speakers definitely don't mean "a condition of humiliating disgrace or disrepute" by "shame". But for many non-native English speakers, it still sounds rude and offensive to listeners. For instance, I never dare to say to my professors that
(3) It's a shame you haven't return our midterm exam papers.
I feel like, though I am not sure, that I should always try to avoid saying "it's a shame..." to anybody that I should show respect to(am I right?).
So I wonder if we can replace "it's a shame" in (1)(2)(3) by other phrases(as polite as possible) in order to avoid the possible offending.