People have had this misconception for a long time about Google, I remember having this debate on HN 4 or 5 years ago. I'm not sure Google has ever supported truly exact string matching.
Mind you, it's overloaded now; double quotes also mean "this term must appear in the results." Used to be that prefixing with + meant that, but they killed that function so they could use it for Google Plus. You used to be able to search for, say, "annie oakley" "wild bill hickok" and find pages with either or both of those complete phrases; now there's no obvious way to do that.
Many years ago, IIRC, Google Search also supported boolean AND/OR, but that was also removed, for no obvious reason.
That wouldn't prevent them from denoting booleans with special characters (which they already do with other functions--see https://support.google.com/websearch/answer/2466433?hl=en), or having some kind of "advanced" interface. As far as I've been able to tell, boolean searches have been entirely removed from Google's public-facing search. There was no need to do that.
If you want it as a default, add it to your browser as a search engine plugin: http://mycroftproject.com/search-engines.html?name=google+ve...
Or: Search tools → All results → Verbatim