The three workers are working on a useless job without a target ('.. until there is an end to these tracks'... yeah, right...)
Kino just told a story about a land where all the people know they are doing a useless job, bit think it was 'a great system'.
Now the viewer thinks about what a bunch of idiots they are... But the workers' question and the lack of an answer show us that Kinos travels also have no target other than just traveling...
Throughout the whole series she is being called a 'traveler' like you would call a politician a politician and a scientist just that. It is her job, but isn't it a senseless job without a point, too?