Maybe she has a bad back, and doesn't want to strain her back.
How many times, have you seen the guy carrying his wife, girlfriend, sisters backpack.
I would probably do the same thing.
Both the poker players have one. The flight attendants from last year had them. Prior to that, I don't remember seeing any team or 1 team member using it during a race leg.
Like I had said, if they were going to use the wheels during down time, it would make since. Giving your back a break as you walk from the check in mat over to where you are going to actually take the 12 hr break or get picked up to go to the facility. But to use it when you are hurrying to try and catch a tram, as in last night with the poker players, and it is actually making you just walk, instead of running for the thing, just doesn't make any sense.
If I was going to apply to be a racer and my partner to be wasn't able to carry or mostly carry their own back pack, I would be looking for a different partner. If carring a backpack is too much for them, I would hate to see what they would do if faced with some of the harder, more physical challenges.