Just like with touch on touch off smartcards, they show up the gross incompetence of the rest of the UK bus industry. Trent Barton introduced their Mango smartcard more than a decade ago and still no other UK operator uses touch in touch out smartcards to pay for variable single fares, preferring the painfully slow driver interaction method which is only marginally improved with bank card acceptance. The rest of the industry brags so much about accepting contactless payment when all they are doing is replacing the cash with a card. You still have to have a time wasting conversation with the driver.