If you have a modern credit card that has touch and pay or paywave functionally built into it, it means if you lose it, before you report it as being lost, anybody can use your card to purchase up to $100 worth of goods or services at a time, without putting in a pin number or anything. They just have to touch the card at a cash register. And that could be done multiple times before you realise you've lost your card. So a modern credit card is as good as a few hundred dollars cash.
Look at the photos in this article: Police investigate use of stolen credit card. https://m.sunshinecoastdaily.com.au/news/police-investigate-use-stolen-credit-card/2819571/
Although unlikely to happen it is possible for someone to put a device close to a credit card and have a transaction recorded against it, whilst that credit card is still in your physical possession. This is a reason that some people keep credit cards in special containers that block radio signals. A mobile phone used as a credit card does not have that problem because it only works when the phone is unlocked.
A card registered on a mobile phone, that has the appropriate security locks on it, can only be used by the person that knows the code that locks the phone. Which should only be you.
If you lose your credit card or misplaced it there's no way of tracing where it is. A smartphone, you can ring from another phone and it makes a noise so making it easy to find.
Smartphones can be set so that you can get it to show the exact location where it currently is. You can't do that with a plastic card.
With a secondary smartphone or a computer you can enable or disable the use of the credit card facility stored in the phone at any time completely independent of your financial institution. The only way to do that with a plastic card is to contact your financial institution.
When you use a phone with credit card functionality built into it, when you wave it on the device not only does the device tell you that has worked but you get a indication on the phone to say that has worked as well as a notification message, which can stay on the phone for quite some time. So until you wipe notifications you can see all the purchases you have made using the phone method. That's not the case with a plastic card.
You have to have a phone that has Near field Identification (NFI) functionality. This is usually available on most modern smartphones. Then you either install an app from your financial institution or from Google Wallet and follow the appropriate steps.
To be able to use the service you also have to have a working internet connection, have it switched on as well as NFI switched on.
Where would normally use a credit card to touch at a cash register you use your phone. The phone has to be switched on and whilst it's being touched and unlocked. This is the security part about it, unless somebody can unlock your phone it can't use it as a credit card.
The functionality is not limited to just credit cards it can be used on debit cards or many other cards that have financial transactions associated with then. It can often also be used for loyalty cards. It alleviates the need to carry a round big bunch of plastic cards.
Perhaps in the future governments will get round to the idea and you won't have to have a plastic card for your licence or Medicare.
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Interesting that this Government article does not mention that a phone is more sucure than a physical card.
Should we be able to say no to tap-and-go technology?