Are canards actually more efficient?
No. It's not true in practice.

While the conventional layout puts the whole tail into the downwash of the wing, a canard will add downwash to the center wing and upwash to the outer wing. This means that while the tail of a conventional layout sees less angle of attack variation than the wing (which is good to prevent tailplane stalls), the up- and downwash variations with varying angle of attack will spoil the lateral lift distribution on the main wing of a canard airplane and increase its induced drag.
Since the canard surface needs to fly at a higher lift coefficient than the wing for natural stability, it will have less margin for control. It is no coincidence that successful canard designs are unstable. Also, this means the big wing surface cannot be fully used for lift, which is wasteful and increases take-off and landing speeds.

More on this can be found here.

Since I was a kid I have read endless articles about how canards are more efficient …

The reason for this is simple. It is much more exciting for authors to claim they know better than all the experts than to humbly admit that the state of the art is really the best under the circumstances. The incentive to laud canards above all else is much too enticing, and human psychology tends to prefer the sources which confirm a preconceived opinion. In the end the authors really think they have found a better solution and become evangelists for a better world, especially when their own understanding of the matter is limited.