How exactly? Does that ever happen to anyone? In UK it's very common to give your card details over the phone(which is stupid, but unfortunately that's how the system works) and I don't think your call being intercepted is much of a concern.
Not sure tho, I don't want to tell someone my credit card info over phone in any case. Someone around you can be listening to you, or even worse, recording you.
Sure - in the UK a lot of companies don't offer any other way to pay them, or the way is a lot less convenient(you can pay with your card over the phone and have the order shipped today, or you can send us a cheque and we'll get to it in the next 3-4 weeks).
Same for any web server unless the app hard-codes a specific certificate. Otherwise any CA can issue a certificate for any domain by default, CT can only catch such a thing after it happens. Don't know if uber.com has CAA records.