It's easy. You select the max amount (up to NZ$200), tap your card, and it's done. Pick up the right fuel nozzle, refuel, and go. Exactly the same can be done on EV chargers.
The process card-side is not a charge-and-refund as refunds have fees to the merchant. Rather it's a pre-authentication and finalisation. Pre-auth holds the funds for a set time (determined by the merchant agreement with the bank) and the vendor can finalise the charge up to the pre-authentication amount. Most hotels and car rental places do this for security deposits as well, if they don't charge or explicitly cancel your bank will release the fund hold at the end of the holding period.
In terms of PIN check, the card is just declined with an appropriate error message because you can’t insert it and the next time you use a contactless machine it asks for the card to be inserted and a PIN entered.
For petrol (gas) pumps in the UK it generally auths either £1 or £99.
I guess the issue then becomes relying on contactless (only) without the hardware for full EMV with PIN, as then someone whose card has been used contactless one too many times can't charge, and potentially ends up stuck there.
It does feel like contactless is a good convenience measure, but probably isn't ideal as the only mechanism on a reader for charging infrastructure.
Unrelated to this, but not being able to initiate charging without internet access (for online auth of cards, and the ones that can only be used online) also is likely to become an issue in rural areas, as well as give quite a few resilience issues if cloud infrastructure isn't available, or internet backhaul from the area is disrupted. Even once power is restored after a storm, if comms are down (like with Storm Arwen), this doesn't sound ideal for EV charging...
If the pump pre-authorizes an amount (many non-Costco gas stations I go to make you choose an amount to authorize) it simply never captures more than was actually used.
Now why would any of this be fundamentally different for EVs? You have a rough gauge for how much "fuel" i.e. "juice" you need, pre-authorize enough money but only capture what actually got used. Done. Why do EVs need to be special?
Not that there's likely to be any real repercussions in many places given a lack of criminal enforcement around theft/fraud, but EV charging requires the user of the stolen card to stick around in a given area to charge the car, so it's likely lower risk than other places where a stolen card can be used for a large transaction in a short period of time.
I imagine you'd eventually get some people going around offering people "cheap" EV charges for free (for cash), and then tapping a stolen card on the reader, but there's always going to be someone trying to exploit stolen cards in innovative ways.
(I believe there are some limitations on tap-to-pay transactions to prevent a merchant presenting the transaction with a different value after actually tapping the card.)
I think a lot of "pay at pump" fuel stations require a full insertion of the card to pre-authorize a large amount, then release it as a partial refund once the amount of fuel dispensed is known.
Would this be a barrier to EV charging, if you need a way to communicate this upfront, or have to effectively replicate out EMV infrastructure on totally unmonitored terminals with PIN readers (and likely the next card skimming scandal brewing)?
Also, how would contactless-only work for cards that get soft locked to be inserted for a PIN check? Would there be a way for EV chargers to be exempted from this? Or would people end up stuck and unable to charge as there's no available place with a PIN reader they can use to unlock their contactless payments?