I opine it has to do with which language the -age suffix was borrowed from, Mr H.
We see pronunciations vary in words that have ough in them.
rough though bough through
and the 'awe' sound in thought.
-age entered English through Old French from Latin. Lotsa things get changed along the way. English as a language had both the Great Vowel Shift and the Great Consonant Shift. Academics think that we only have about 10% of our original language (Old English, sometimes wrongly called Anglo-Saxon) still with us. Irish monks saved what there is left of it when Norsemen raiders were looting and burning the books that then existed in monasteries.