Can you tap your contactless card at the barriers to pay for several passengers, e.g. by handing the card to the next one coming in? Or this this method only for single travellers?
https://tfl.gov.uk/fares/how-to-pay-and-where-to-buy-tickets...
Let‘s say you have:
1 contactless bank card, 1 iPhone, and 1 Apple Watch
These count as three different cards and would therefore allow you to pay for your own fare and two additional people.
If you have more than one card you can let others in your group use those.
Though it’s been a few years since I was travelling with anyone who didn’t have either a contactless card or Apple Pay / the Android equivalent, which also works and is arguably even more convenient.