for a glimpse of the future, consider the new International arrivals terminal at the Calgary International Airport.

previously, international arrivals were asked to pre-fill the standard Customs form, and weave their way to a series of manned kiosks where a human agent reviews the form, and sends you on your way to the final area exit, where an agent reviews the previous agents assessment and send you on your way.

Agents encountered - 2 

Now, an agent greets you in front of a gleaming bank of automatic customs forms readers, telling you, and everyone else, to find an open machine.  That's 1 person.
Then you insert the form, the machine does its thing, and prints out a facsimile. Another agent directs you to a lineup. That's 2 people.

A person at the head of the lineup reads the machine generated form, and then either directs you to the same old lineup of manned kiosks, or to the luggage carousel. That's 3 people.

Then one final review, and you're free. That's 4 people. The future