Many Americans are at the very least cultural believers. They celebrate Christmas and Easter and get warm fuzzies while watching "Highway to Heaven" and "Touched by an Angel". They have this vague idea that after death they will be reunited with their families and live happily ever after with a loving God who takes them in. They may not go to church often, but at the funeral there is lots of talk of seeing Aunt Agnes in the by and by.

So when the Mormon missionaries come and visit them, they are being sold something they already believe they have. When told they will have to pay 10 percent to attend a temple to get their family into heaven with them, they generally won't buy because they already believe they have that for free. But the poor brainwashed Mormon thinks if they don't pay up or if their kids refuse to pay up they are doomed to a painful separation. Aunt Agnes didn't pay her dues so they won't see Agnes in the sweet by and by unless they pay up and go to the nearest temple to at least give her a chance to get in. Mormonism holds the power to keep Agnes out.

Sometimes you see signs on the Florida Tollway suggesting that Jesus already paid your toll. Doesn't work with the toll booth operator, but the suggestion is clear that God doesn't expect anything from you. But the Mormon missionary continues trying to sell his product and sometimes people fall for it. You may get into heaven, but you won't be exalted with your family. No wonder so many people reject the product. Why pay for something you already think you have?

Good question, and my jaundiced opinion is this: "follow the money trail". Yes, Jesus has already paid the price (IMO), but the early leaders and members of TSCC (BY) said that wasn't good enough and that there were some sins that could only be forgiven by the shedding of blood. TSCC worships a god of fear and money. Paying tithing isn't good enough; there's the costs of magazines, YW's camp, paying the ward's scout program $50/year to have US flags posted in your yard on holidays, the ring of the cash registers renting temple clothes if you forget anything when you go to the temple, paying out of your own pocket for activities, etc. TSCC is a cult and a profitable racket for the GA's.

But...I don't already have magic underwear.
And I don't already have a huge time-sucking 3-hour set of meetings on Sundays.
And I don't already have absolute, blind obedience to outdated and rather silly 19th century "health" rules, since modified heavily.
And I don't already have every third Saturday scheduled to go clean toilets at a place I can't stand being in.

So, see? They DO have plenty to sell that we don't already have!

(one of the not-so-many Americans who doesn't fit any of the "cultural believer" things you put up front)