I agree, but multiple people can scan a QR code simultaneously.
If it's large enough, and posted in a place where people sitting around a table can all see it clearly.
Maybe I missed the point, but the aside about parking metres seems irrelevant. Just makes me think this is an anti-technology rant.
And again, the gripe about splitting up the bill. Not only is that a problem with existing systems, it's a problem that is solved by QR codes (if implemented correctly).