Except shipping packaging (even when pared down by Amazon) is rarely designed to show off the object in question and such boxes (unless specifically designed for certain objects) would have quite a bit of wasted space in the storage units.

Further, you're basically operating a vending machine at that point, but with limited inventory, space losses, undesirable packaging and an undesirable location. (low foot traffic)

The obvious improvement is to just make a proper "redbox for things" vending machine, designed around a few optimized packaging dimensions and start leasing more-visible/accessible spaces to host it.

But what is that, if not just a (small) robotic convenience store? If you could pull off such a machine, why not just build a larger version and outright compete with 7-11?

A couple Swedish online computer retailers now have storefronts in the countries largest cities where you can opt to pick up your orders to avoid paying the shipping fee (the storefronts have nothing to browse, just a window to pick up/pay for orders), and they do this with the most common stock.

It tends to add another week of package receipt delay in my experience. Maybe the location I use is just crowded.