If they are adults it is often too late. Also, therapy can't fix every single case.
Agreed. Not every single case, but I would think that a vast majority could have been treated when they were younger. I am not saying anything is wrong with the individual (though I've seen adults work hard on changing their accents), but I grew up at a time and environment where speech therapy was no where as common as it is today, but parents spent time and effort to get their kids to pronounce things correctly.