Why are the prize values in Master Key and Rat Race (as well as the bonus prize in Clock Game) never announced?
They could, I suppose, but I'm guessing it's to make a cleaner presentation.
For Master Key and Pay the Rent:
1) It doesn't make sense to describe the prizes as a "prize package" since the contestant can win any combination of the three prizes offered.
2) The home audience doesn't really care that much. The focus is directed towards
if the car/prize is won, not on the value of the prize.
For Clock Game: In addition to #2 from above, you risk making the gameplay less smooth.
If you give the price of the whole prize package, you might end up misleading a nervous contestant into thinking, "Hmm, the whole prize package is $7,500, there's 3 prizes, what's 1/3 of that?" The audience can't do anything to correct them, so the game would end up in the game going something like this:
"$2,500." "Lower." "$2,400." "Lower". "$2,300".
That'd be painful to watch.
If you only give the price of the bonus prize, same deal. You're putting unwarranted focus on the bonus prize. This could throw off a contestant who doesn't realize they need to be focusing on the cheaper prizes, or that the other two prizes ARE significantly cheaper.