Nowadays, the term ‘Reb’ or ‘Rabbi’ is basically the equivalant of, lehavdil, ‘Mr’. And before you point out that ‘Rabbi’ appears to denote semicha or a position, the term ‘Mister’ was originally only used to address one of superior status, but in modern times is basically a catch-all honorific. I believe it is not unreasonable that the same applies to ‘Rabbi’. And if you wish to challenge this cheapening of the title, may I just point out that it is far better address a Mr as a Rabbi than a Rabbi as a Mr.
And if you were to argue that this leaves no suitable terms for those who deserve them, two points. Firstly, that the term Rabbi as a title, certainly in my community, is reserved for actual Rabbis in any official context, such as on letters or posters. And secondly, that Harav or similar is generally used with what we nowadays call semicha.