An interesting discussion came up in the chat following a sentence I suggested in another question where I said something along the lines of "I apologise that I have a prior commitment." or "I apologise that I will be unavailable this evening."
To my eye and ear, this is a perfectly valid construction, where "I apologise" has almost the same meaning as "I'm sorry" and can therefore be used in place of it, but general consensus is that I'm incorrect and this is ungrammatical or at least incredibly rare.
Now I understand the subtle difference between the definitions of "sorry" and "apology":
Sorry—feeling regret, compunction, sympathy, pity, etc.: to be sorry to leave one’s friends; to be sorry for a remark; to be sorry for someone in trouble.
Apology—a written or spoken expression of one’s regret, remorse, or sorrow for having insulted, failed, injured, or wronged another: He demanded an apology from me for calling him a crook.
so I'm really only asking in the context that the apology is for failing or otherwise inconveniencing someone (as having a prior commitment might).
The ngram and COCA results do indeed point to this as a highly irregular use, but there are enough results that I can argue its validity even though it's clearly less common than "apologi(s|z)e for" and I'm really curious as to whether anyone else considers this valid, has heard/seen it used, or can confirm whether this is possibly a dialectal or regional quirk. Or maybe I'm just completely wrong and should stop saying I apologise that things.