True – and at least with the bikes, you’re on the street and have other options available (taxi, bus, minicab) if your journey is time sensitive.
On the underground and overground rail once you get stuck between stations you’re at the mercy of the system. Often when you’ve swiped (and paid) to get into a station and down to the platform, only to encounter delays, it’s tempting just to wait there in the hope the problem is sorted out. But it can be a long wait. If you swipe out after five minutes or so at the same station, is a journey recorded and charged on the oyster card?