Contactless transactions using your phone are fast, secure and easy. Over time they will replace almost all current usage of chip & pin or magnetic stripe.
Fraud clearly hasn't had a deleterious effect on the entire system, and the penalties for fraud align incentives to fight fraud properly. It's not such a large problem that I'm willing to take steps backwards in terms of functionality and privacy to digitize my purchasing.
And mobile phone providers over here don't guarantee even two nines of reliability, never mind that even 3½ days of no service per year is already too much for some critical things, like being able to get at your money.
And the local public transport association for example tries to disclaim any responsibility for any sort of problems if you're using their mobile ticketing app – if it doesn't work, though luck, your problem, buy a new ticket or pay a fine. Even if you've bought a monthly season ticket there are no special provisions, and the rules don't even differentiate between technical issues caused by myself [1], those caused by third parties (like the mobile service provider) or those caused by the public transport provider respectively its app developers themselves.
[1] Although while I can take care to keep it sufficiently charged, not letting it fall to the ground or whatever, I still can't prevent it from just randomly dying anyway, or the manufacturer issuing some borked update or whatever
Powered devices like a phone have read/write NFC chips that the device will write data to on demand, usually waiting for some form of user auth to make it secure, e.g. an iPhone keeps the NFC chip empty until you specifically request to pay for something, at which point it authenticates you (e.g. with FaceID) and then writes the data to the chip which can then be read by the terminal to authorize payment. Once payment has been made it wipes the NFC chip again.
But a device can have some payment info written to the NFC chip at all times, which is what iPhones do when you have the "Express Transit Card" option enabled – with certain authorized vendors, that payment data stays on your phones NFC chip indefinitely, so you don't need to auth with FaceID and even when the phone is out of battery it can still be read by those authorized terminals.
I now need a phone that I keep charged, up to date, with cellular connectivity, and logged into some tech behemoth in order to pay for goods?
plus on the bus or train I usually use a book or my kindle so it's easy to forget the phone