Perhaps the plan is all about using customs agents more effectively rather than saving time for passengers. I could imagine a situation in which agents only deal with passengers who have items to declare, or who get flagged for secondary inspection at "self service," green lanes.

It needs some refinement, and it sounds like good advice to have a paper form as well as a QR code at the ready. On my Air France flight earlier this year, the flight attendants ignored my request for a paper form. Turns out they had run out of translated forms. I eventually persuaded them to give me a Japanese language form.