I start this thread looking for a reason I'd actually pay that difference, and didn't get reasons, I simply got told to use thinset. That's less than reassuring IF I don't know who I'm getting advice from, which is the case here - an explanation (which is all I asked for in the first place anyways)
In the future if you were to bother to take a look at the profiles that people have filled out here (unlike YOU) then you would have a better indication of who was answering your questions. Had you bothered to check some profiles you could have saved everyone a lot of time.
When you approach a stop sign in your town do you contact the city council and insist on an explanation as to why THAT stop sign is at THAT particular location? You don't know who put that stop sign there but still you know you should stop for it. Do you know how much a stop sign costs? Those suckers are expensive. Why couldn't the city just make a stop sign from cardboard? Even if they replaced it once a month for twenty years, it still wouldn't cost near as much as the real thing.
I just removed a tile backsplash and counter that had 3/4 inch of what I believe was portland cement installed in the forty's. I shook the whole house and the tile would not pull away from the cement. But it was all different than, things have changed, different tile, different installation and different portland cement.