Why are shoes typically made with an inward curving back?

Breaking in a new pair of shoes right now and one problem I often have is that the top part of the heel section (where there is sometimes a loop attached for pulling on the shoe) curves back in, pressing on my Achilles tendon when the shoe is worn - you can see the curve in this product
For me, this always rubs really badly and results in a serious blister, until the shoes soften and stretch.
Now, some people will no doubt say that I should stretch and soften this part to shape it before wearing the shoes, but why not just make it so it doesn’t curve in there?

Is it that I have odd shaped feet, and most people need shoes to curve inward there like that? Is it because if they made it to fit, it would stretch to be loose?

It curves inward to follow the shape of a human heel. It helps hold the shoe on your foot (when done properly)

Of course, humans being critters, we vary in shape, including the shape of our heels. Your feet may be a bit of an outlier.

That said, shoe makers also vary and there are some poor designs out there that curve too much on the back.

So it might be the shoes you bought and it might be you and it might be a combination.

As for the solution - you already have it. You’ll need to soften/stretch that part of the shoe slightly before you wear it.

It’s definitely not just you. Whenever I got a new pair of leather dress shoes, I used to resign myself to having bloody socks the first few times I wore them.

This is a reason why I mourn the loss of shoe stores. The shape of a shoe fitting the shape of my foot is very much hit and miss. The last time I bought a pair of dress shoes, it took five purchases and four returns before I found one that was comfortable. Most of the “failures” were exactly what you are describing.

I used to go into a Clark’s or Bostonian store, or even the shoe department at Macy’s, and try on 20 pairs of shoes and find a good fit in less than an hour. But there are hardly any stores around and those that are have an inventory so thin that I can’t find 5 shoes in my size, never mind 20.

I have a terrible time breaking in certain shoes. I’d have blisters on my heels for weeks. I would have to buy giant Bandaids and apply them whenever I wore the shoes. Now I just stay away from certain brands like Nike. I never have a problem with Skechers or Filas. I don’t think I own any regular shoes that have backs anymore. Other than my beloved Skechers in all styles and colors I wear boots (which I never have a problem with) or sandals.

I have the same problem and have used mole skins on my ankles to avoid blisters :

Dr. Scholl’s Moleskin Plus Padding Roll (24" x 4 5/8") / All-Day Pain Relief and Protection from Shoe Friction with Soft Padding That Conforms to the Foot and Can Be Cut To Any Size https://www.amazon.com/dp/B007W9MGLI/ref=cm_sw_r_cp_api_glt_fabc_2VA05X3KJS7J0HQ4RXMF

I have also resorted to buying shoes or boots with zippers.

I’ve had the same problem. Now I almost always buy shoes that have an “Achilles notch” in the trouble spot. It really helps. According to this page on running shoes

It’s harder to find street shoes with an Achilles notch, but they exist. Some of Rockport’s casual and walking shoes are good that way, but not so much their dress shoes.

I use a hammer to stretch out the back of the shoe - position the edge of the shoe over a block of wood or corner of a cutting board, and hammer away until the shoe is stretched out a tiny bit.

Yes, it follows the shape of a human heel.
squints eyes suspiciously

I think I’m going to build a stretching jig - it looks like you can only buy shoe stretchers that address the toe end of the shoe, either widening it or pushing out in one place.

That is the usual cause of blisters on the ankle for me. I have wide feet and if the front of the shoe is not wide enough, I end up buying shoes that are a size bigger (lengthwise). This means that the shoe is not snug on the ankle and causes blisters.

A bench-top anvil with a curved edge works for hammering the shoe ankle edge against.

Works even better if you marinate in a solution of enzymes overnight first.

Is the problem really that the shoe curves inward there, or is the problem really that the shoe has an edge there that digs in?

Compare with a high-top shoe, as seen here:

The inward curve behind the Achilles tendon is plainly obvious here but it’s not at the top edge of the back of the shoe, and it doesn’t dig in. Not to mention that, being made of canvas, no pre-marination is needed.

ETA: I’ve been wearing Converse All-Stars High-Tops and nothing but for the last 40 years – originally for a totally different reason, but ever since because they are cheap(-ish) and comfortable.

Both. The inward curve on boots is definitely present, but seems generally more subtle in general than I have seen on shoes, but yeah, also the edge - just because there is an edge, and also because the edge seems to turn a curve into a curl - that is, the rim of the edge turns (somewhat) sharply inward, when the body of the shoe is in tension

So the solution is . . .

. . . wear high-tops!

Sure, for walking any distance, I’ve got hiking boots, but high tops and boots are a PITA to just throw on for a quick trot out to the car, or down to the shop

Maybe I need to get some Chelsea boots

back door shoes

I’m looking forward to an Atomic Shrimp / Harry Rogers YouTube shoe-making collaboration!

I have shoes similar to those that are used to run out to the garage, the mailbox, etc. In the summer an old pair of flip-flops takes their place.