If you have access to internal industry statistics, and you can show these, then fine. But I'm working off the following:
https://www.money.co.uk/credit-cards/credit-card-statistics
As of October 2021, there were approximately 52.97 million credit card accounts in the UK, with almost two-thirds of these (34.79 million) being active (those with balances outstanding at the end of the calendar month).
65.6% had balances outstanding (not paid off in full) then.
Also:
Transactors, which make up 8.5%, will pay their statement balance in full every month and generally have one of the better average scores on Experian’s aggregated bureau index.
Representing over 11% of users, revolvers do not pay their outstanding balance in full every month and will incur a resulting rate of interest on their credit card debt. As a result, their bureau index score is severely less, at 895. Hardcore revolvers are the most popular group. At 31.5%, these people only pay the minimum amount each month, which in turn produces the lowest average score of 803 (over 200 points less than transactors).
Transactors paid their balances in full very month. Revolvers do not, and hardcore revolvers only make minimum repayments.
Finally, a couple of articles that show credit card companies make greater profits and revenue from interest than they do from transaction fees:
https://www.federalreserve.gov/econres/notes/feds-notes/credit-card-profitability-20220909.html
https://www.fool.com/money/research/credit-card-company-earnings/
I admit, none of these sources are perfect, they are what I have access to in the middle of the day.
So, if you have evidence that the credit card industry is structured very differently in the UK to the USA (or the ROW given VISA and MasterCard are multinational), or that UK borrowing habits are much better now than they were in 2021 I'm happy to be shown to be wrong.