But it's not like NFC based card would solve this problem, you should still give a permission (I think) if you want the contact to be added to your phonebook etc.
I understand you have to put the card very close, 3-4 cm or so to the phone but otherwise it would be good way to troll or scam people... create a fake card and the name would be Your Mom, actually call to a friend/extremely expensive number... or things like that.
NFC could easily be implemented so that permission isn't necessary, but even then tapping on one's screen (only the sender has to tap in the existing implementation of Android Beam) is much lower friction than scanning a QR code.
swipe>unlock
password> 123456
AppX>locate, open
Permission?>Y/N
Its not frictionless either way. NFC cannot be trusted. You need to aknoweldge Y/N prior to letting anything write data onto a phone. Too much risk otherwise.
You don't need to location AppX, the Android Intent system (Android being the only consumer mobile platform with an NFC implementation at the moment) can respond to the data in the NFC tag and open the appropriate app.
I'm not claiming it's frictionless, but just that there's less friction than a QR code.
I understand you have to put the card very close, 3-4 cm or so to the phone but otherwise it would be good way to troll or scam people... create a fake card and the name would be Your Mom, actually call to a friend/extremely expensive number... or things like that.