1. There is one road in and out of the second location they had to get to. It was either the road through Canada, or take the longer route with 2 border crossings to Alaska and back then arrive from the other direction. Look at the map to get a sense of how remote those locations are, and how it is highly likely they would be seen together at the same time.
2. The first couple to arrive at location two were a full 25 hours ahead of the second. There has to be a degree of tension otherwise the show doesn’t do what is says on the tin, so you won’t get a real sense of where each of them in relation to time/each other until they’ve checked in.
3. No point being first at any location until the last one, whether to spend money now or later is the leveller. In this series the options increase as you move east, the Cockney geezer and his daughter spending 500 dollars on a taxi could be a genius move or a chance wrecker….who knows.