When they have to wait, they are affected on the next leg of the race by having a delayed start time.
For example, the second to the last team arrives at the challenge 5 minutes after the team ahead of them. The team in last place is lost and is two hours behind. If the second to last place team wins the challenge, they still have at least a two hour deficit on their start time.
If they lose the challenge to the last place team who is two hours behind, that is still an unfair situation.
I do see what you and others are saying, and it is a valid approach. Several rules/forms of challenges in this game do not seem fair to me, but i'll talk about it at the end. But since i love this game so much, i would like to "logic through" this cart-challenge/wait issue a bit more..
We are basically talking about "circumstances beyond one's control" and how they affect the race/teams..... This game is FULL of circumstances beyond one's control.. man-made, and accidental.... This one is "man-made", true.... but:
- you're saying that it is not fair for 2nd-to-last remaining team to wait X amount of time for the last team because: the team that is ahead of the last team is NOT rewarded for arriving earlier than the last team. Yes, it is true, which ever team waits for the last challenge depends on the last team's arrival.
But the fair part.. that depends on how one views the segmentation of this challenge..
A - each team's arrival to the cart challenge after diamond/print challenge.
B - next team's arrival to the cart challenge/start of challenge.
C - the time the winning team advances to the next leg.
If you look at this segment as A and B as separate parts of the segment, then yes, last waiting team depends on last arriving team - [A] +
= C.
But, if you look at A/B as "one segment/continuing challenge", [A + B] = C, then ALL circumstances between "diamond/print" and "winning cart race" are part of process.
Let's not forget, that the 2nd-to-last arriving team, does not have to wait for the Last Team. 2nd-to-last has an opportunity to race against 3rd-to-last remaining team, and proceed. If they don't win from previous team, only then they wait for Last Team. So basically 2nd-to-last team (if they have to wait) is "punished" for 1) not winning the challenge on the first try, and 2) being 2nd-to-last team. The Last Team HAS less advantage, they have only 1 try to win the challenge, while 2nd-to-last has 2 chances (so they are rewarded by extra opportunity).
If the 2nd-to-last team wins from Last Team, but now 2 hours behind all the rest, the logic behind it is: 1) they did not win from previous team, 2) they arrived 2nd to last.... later than teams ahead, so they get 2nd-to-last type of disadvantage.. (but not the worst, as the last team).
If the 2nd-to-last team looses the cart challenge to the Last Team, well.... they just did not complete the [A+B] ... and they had to wait for 2 hours because they did not win from 3rd to last team.... and they HAD that opportunity.
So if the logic is that after challenge [A - diamond/print] the teams are not rewarded by having to wait, to me its not quite true: the earlier you arrive, the more chances you have to take the cart-challenge.. The later you arrive, the less "options" you have...
Plus... this is by no means the first challenge/format where a Team depends on CIRCUMSTANCES BEYOND THEIR CONTROL... Broken equipment, change of weather, animals acting out, taxi/boat driver's abilities, etc.. But the worst man-made one is U-TURN! that is the worst unfairness of the game, that team/teams are allowed to gang-up on the "best Team"... this is a legalized "Tonya's knee-wack" if you think about it!
Also, for me, the biggest unfairness in this game so far, is in the 1st Segment, in Iceland. The 30-minute penalty to basketballers, for looking at others' ice-cube spelling is not fair! Why? Because in ALL previous season in many challenges teams a) were helped by other teams (got answers, directions, physical help), and b) were located close enough to another team to see what they were doing, like the "sun chair assembly" challenges few seasons back, and help with "metal spaghetti spoon" challenge in one of African countries, help with loaded bicycle challenge last season, teams teaming up to seek directions, agree to follow each other, share information, etc..
I think it is "shitty" that Basketballers had to sneak a pick... but i also think it is "shitty" to get answers and help from other teams, or look at their work which happens several times each season. Why punish basketballers now?
Woulda never ever been able to haul my fat butt up that ladder. 
That game would have been fine as a challenge, but they should have had to do the "pick a pair to play against" thing and play against some local experts like they have done before. I liked the Old Dudes. 
