There's also the time-budgeting aspect. I know it will take me two minutes to order dinner on Deliveroo or book a doctor's appointment in the NHS app, but if I have to ring someone, numerous factors could affect how long that takes — lots of calls at once, not enough call-answering staff, they need more security on the phone because I'm not just magically logged in, I have to spell out my name/address/postcode twice, etc. There's no way to tell for sure how much time such an unpredictable interaction might take, so it's more difficult to set aside time to do it during a busy day.