It's time for zero-drop to include toes too. Common examples of what is known as "TOE SPRING" can be seen below:
Natural Footgear writes:
Toe spring is a toe-deforming shoe feature present in most shoes, including athletic shoes. Toe spring is the elevation of your shoe’s toe box above the ground or supporting surface. The current industry standard for toe spring for most types of footwear is 15 degrees. This means that most shoes hold, or immobilize, your toes in an unnatural, extended position.
From Dr. William Rossi:
So why is toe spring built into the last and shoe? To compensate for lack or absence of shoe flexibility at the ball. With toe spring, the toes of the foot are constantly angled upward five to twenty degrees, depending upon the amount of shoe toe spring. Functionally, they are “forced out of business,” denied much or all of their natural ground-grasping action and exercise so essential to exercising of the whole foot because...18 of the foot’s 19 tendons are attached to the toes."
Not only are toes being squished inward in the tapered toe boxes of today, they're being bent UPWARD. That toe spring shape, like a cast, is holding the metatarsal joints in a dorsiflexed position. In standing and when moving. Check out the muscles of the foot who's tendons are attached there:
Check your shoes. All of them. If you have kids, check theirs. Do a little math and see how much time you're spending with your toes up.
Have a look at your feet out of your shoes, non-weightbearing. The following photos are of a friend who stopped over after a bike ride, relaxing in his chair. This is what I'm talking about. See side view and front view. The x-ray is not his, but pulled from the internet, labeled as a "normal lateral foot xray."
Although the image below is from an article about hammer toes, I liked the visual. Have a look at the curve of the toe joints (Mr. Big Toe has two the others have three!) and the whoopdedooing tendons that never have a chance to lengthen out to full tension to transfer power.
I'll leave you with food for thought from Dr. Rossi's article Why Shoes Make Normal Gait Impossible:
We have always assumed that most people in modern shoe-wearing societies walk "normally." It is true only if we use the term "normal" in its liberal context, meaning to conform to an accepted standard or general average.
But natural walking -- the pure manner without faults of form or function -- is quite another perspective. All ambulatory creatures in nature walk naturally, hence with maximum efficiency. That includes all shoeless people, who are the only "pure" walkers on the planet. All the rest of us, by grace of the shoes we wear, are defective walkers in varying manner or degree. And who knows how many of our foot problems stem, directly or indirectly, from those shoe-caused postural and gait faults.
Does all this suggest that the only means of retaining or regaining the natural state of gait is to go barefoot? Unfortunately, yes. That is, until the "ideal" shoe, devoid of all the faults of design, construction, and performance of traditional footwear, is made available. But, throughout all history to the present, nobody has yet designed such a shoe while at the same time providing the esthetics and styling desired by consumers.