Yes, that's where I was going with my reply. By that token, the HIGHER/LOWER aspect of Bonus Game has always been tougher than Punch-A-Bunch because your odds of winning the top prize with each correct guess are 15 times greater in the former.
If you want to force a win in Bonus Game, you only need to make one SP price easy to guess; in Shell Game, all 4 need to be easy to guess!
What I think may have been the greatest example of a forced win in TPIR's history happened in an early '90s playing of Bonus Game. The contestant lost the first 3 SPs. The 4th SP was a Monopoly board game. The wrong price was $7, the contestant correctly guessed higher ($11), and the BONUS was in that window.