I think it's actually more useful to think in terms of "2 minutes between them", as opposed to "23 miles".

2 minutes is all you have - to detect the situation, make a decision, then stop.

How much time do you have in heavy freeway traffic?

Four seconds, if you're driving the way you were instructed. But you've got multiple options: go left or right, and if you slam the brakes they'll stop you in time. If something broke the tube, are we looking at several pods slamming into the obstruction one after the other?

The two situations you're comparing are vastly dissimilar.