I may be misunderstanding your question, but you can't use an Oyster card or a Contactless payment card for more than one passenger. If this is not what you mean, perhaps you can explain the circumstances you are thinking of in more detail.
London bus tap ins give you unlimited bus and tram tap ins for an hour after you make the first tap under the hopper fare scheme.
If you tap again after an hour you'll just eb charged another £1.65
My understanding is that you can only touch in once on the same bus making the same journey. The bus computer is reset at the start of each journey. If revenue officers board they download a list of the cards validated on that journey and then get each passenger to present their card for checking. They would absolutely notice and have a huge problem if more than one passenger claimed to be using the same card.
Not so. If the OP were to touch twice on the same bus 30 minutes apart there would still only be one charge made.
Would it? You would certainly have an extremely confusing journey history, as Apple Pay contactless journeys are normally included on the actual card's journey history, I assumed the back office system treated them as one, but have never tried it.
So you tap on a bus, five mins later you jump off and get sone shopping. You are near the end of the route, the bus you were on reaches its terminus, sits for a few mins then starts its return journey. Meanwhile you’ve got your shopping and are back at the stop waiting to go home. Bus comes along, it’s the same bus you were originally on, so tap, five min journey, get off, fifteen mins to get your shopping, two mins later you tap in for return journey. That’s tapping on the exact same bus twice in 22 mins, but it’s seen as a hopper?
Correct. Unlimited bus and tram tap-ins for an hour from the first one. Even if there's a train or tube journey in between
When the bus turns round and starts a new journey the computer is reset, so it's fine to touch in on the same physical bus again. If the touch is within an hour of the last chargeable bus tap then a hopper fare of £0.00 will be charged.
But at what point does it go from being rejected as a pass back, to being accepted but only one charge being made?
It would be rejected if the bus was still operating the same service that you boarded initially - before it reaches the terminus and the computer is reset.
Yep. There would be separate journey histories in your online account for each virtual number you use. I use one card, but have separate journey histories for the physical card, Google Pay and when I use it via Curve
I heard that hopper doesn’t work in the opposite direction. I’ve never remembered this at a time to test it. Is it true?
Not sure this is true - in the days before my nominee pass I'm almost certain I've just been charged for one journey when I've used the same bus to get into my local town, it's gone on to it's destination, returned and I've got back on it to go home. As @MikeWh says the system is reset anyway so I don't see how this would work.
No, the hopper definitely does work in the opposite direction.
Interestingly it was 20 minutes later although I would not be surprised if the time was slightly higher because it is a high value pass.
In My experience it resets after a few stops, on the stand alone readers The pass back message says “card already used on this journey” But if you wait a few more stops you can touch again and it will work, I Don’t Know about the drivers ticket machine reader, but the stand alone readers you can.
Its worked for me in the past
It’s not necessarily a case of being unaware of it, more a lack of understanding of how it works.