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Comment by novok | Hacker News Reader

QR codes are not good for high throughput situations, like subway gates although:

https://atadistance.net/2019/08/13/transit-gate-evolution-do...

But China is in love with the QR code, so who knows how many years or decades it will take them to make their subway gates use fast NFC payments.

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Both have advantages that make them complimentary identifiers and not actually that competitive with each other. Ultimately they promote each other rather than consuming each others market share and I see both last years and years in to the future.

You can print a QR on paper. You can't do that with NFC.

NFC works in low light conditions -- QRs typically don't. NFC chips have allocated uids -- QRs are mutable. NFC is expensive and QRs are cheap. QRs are universal while NFC is tightly controlled.

>NFC chips have allocated uids -- QRs are mutable.

NFC is mutable too; the low-cost unpowered chips you'll buy are mostly write-once read-many, but an NFC device with host card emulation can largely be whatever you want it to be. I suppose it's analogous to a QR code displayed on a screen vs. a printed QR code.

>but an NFC device with host card emulation can largely be whatever you want it to be.

Nope -- even host card emulation can't emulate the UID for obvious reasons. Hence making it controlled.

Well sure, but it can emulate just about everything else. And if you're depending on the UID not being spoofable, well...

https://www.aliexpress.com/popular/nfc-card-writable-uid.htm...

I sort of expect them to switch to facial recognition and do away with turnstiles altogether for most passengers to dramatically increase efficiency once the tech and databases are advanced enough. As in, the system recognises where you entered and where you leave and the fare is automatically deducted from your account. Those who are not known to the system (eg first time users and tourists) aren't allowed enter the station until they set up an account (long term or temporary respectively). The system would have a bunch of problems but the authorities wouldn't care too much as long as efficiency was high.

I live in Beijing, both NFC and QR code work just fine in the subway at the same time.

The QR code video shows a ton of people going through the turnstiles quite fast. The one guy that didn't go through might have run out of credits, and needs to top-up.

So those two videos actually demonstrates that QR codes is actually more than fine. NFC might be faster and more convenient but the difference isn't huge.

NFC gates in Japan take maximum 200ms and can handle one person per second at one gate; the riders never stop walking full speed.

The QR readers are certainly not “quite fast” and that’s nowhere near “a ton of people.” That QR gate wouldn’t stand up even on a weekend at a mid-range Japanese station.

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