Any reason they can't be installed trivially?
>An 'extra hour' is a very long time for someone to wait and I would be surprised if anyone would want to be stuck without access to one for that period of time.
How's that different from most long-way (Greyhound etc) bus rides with lots of hours (3-4) between stops? Don't know about how's that in the US in particular, but had such in most of Europe, Asia etc, and people are perfectly capable of "holding it".
Capsule size. The last I saw the pod designs, passengers are all reclined cockpit seats that aren't going to have a whole lot of elbow-room, let alone any chance to stand. "Holding it" is an option, but it caps trip time at an hour or so. Past that you're going to be hosing down an awful lot of capsules.
And of course it is different from a bus. If a women is pregnant or violently ill on a bus you can stop at any time. And in fact every Greyhound bus I've been on will stop at various gas stations for toilet/food/drink breaks.
It's worth mentioning because what good is the technology of hyperloop if the economics fail (because no one will use it).