The first image I shared is an underside of an M1 MacBook Air, cover removed. I attached it to show how insanely cramped inside.
The machine reaches that thickness under the keyboard. Around the middle Torx screw holding the screen hinges on the top of the image.You can of course carry the thickness like the MacBook Pros to the edge, but there are other problems.
USB-A ports are a bit thicker than the opening themselves. A proper, high quality port has some spring loaded shielding pressing towards the port opening and it flares out, Also, 90 degree ports have some distance between the port body and contacts, since you need to fix the port to the board via quite a few pins (9 pins on electronic side, plus at least two for retention, unless you clamp in down via a retainer, which needs screws, etc).
All of this "machinery" adds quite a space required to implement a USB-A port on a board. As you can see in the article itself, the hubs themselves use "through the board, unflared" ports to minimize space use as much as possible, and none of them are very slim.
The slimmest USB 3.0 hub I've seen is from Anker [0][1], which I also use almost daily. As you can see, you need to have that slack around that port. Same port on a laptop needs same amount of slack around [2][3]. My older MacBook Pro also has similar amount of slack around its USB-A ports.
All in all, a MacBook Air doesn't have the thickness and space to include that port, in its current form. We're always talking about thickness, but insertion depth is at least 15%-20% greater for USB-A too. Plus you need the depth required for supporting the pins on the plug side. That needs to be taken into account, too.
The machine reaches that thickness under the keyboard. Around the middle Torx screw holding the screen hinges on the top of the image.You can of course carry the thickness like the MacBook Pros to the edge, but there are other problems.
USB-A ports are a bit thicker than the opening themselves. A proper, high quality port has some spring loaded shielding pressing towards the port opening and it flares out, Also, 90 degree ports have some distance between the port body and contacts, since you need to fix the port to the board via quite a few pins (9 pins on electronic side, plus at least two for retention, unless you clamp in down via a retainer, which needs screws, etc).
All of this "machinery" adds quite a space required to implement a USB-A port on a board. As you can see in the article itself, the hubs themselves use "through the board, unflared" ports to minimize space use as much as possible, and none of them are very slim.
The slimmest USB 3.0 hub I've seen is from Anker [0][1], which I also use almost daily. As you can see, you need to have that slack around that port. Same port on a laptop needs same amount of slack around [2][3]. My older MacBook Pro also has similar amount of slack around its USB-A ports.
All in all, a MacBook Air doesn't have the thickness and space to include that port, in its current form. We're always talking about thickness, but insertion depth is at least 15%-20% greater for USB-A too. Plus you need the depth required for supporting the pins on the plug side. That needs to be taken into account, too.
[0]: https://cdn.shopify.com/s/files/1/0493/9834/9974/products/An...
[1]: https://cdn.shopify.com/s/files/1/0493/9834/9974/products/A7...
[2]: https://www.anandtech.com/show/16131/a-15inch-thin-laptop-fo...
[3]: https://images.anandtech.com/doci/16131/2.png