On Ambidextrous Design

Whenever I go into gun shops, I’m always confronted by huge amounts of right-handed guns. Granted, 90% of the population is right-handed, but there’s still 10% left-handers out there. That’s not to mention the number of cross-dominant shooters (those who are right handed but left-eye dominant, and so must shoot as if they were a lefty).
Is it really that hard to tell your CNC machine to flip the design over the y-axis? Maybe, I don’t know. I’m a physicist, not a machinist. If you’re a machinist or designer, I’d appreciate any commentary you might have.
Perhaps it’d be easier to implement ambidextrous features in the design phase?
My Mossberg 500 shotgun is easily loaded by lefties or righties (the loading opening is on the centerline, on the bottom of the shotgun). The tang-mounted safety is similarly easy to operate by anyone. Sure, the spent shells eject out of the right, but that’s not been a problem.
My Bushmaster AR-15, however, is not terribly lefty-friendly. Sure, one can adapt to it, but it’s still a bit annoying. For example, the magazine release is only available on the right side, and the selector is on the left. Granted, one can buy an ambi selector ($25) and a magazine release ($95), but they’re pricey and are just hacks to make things work. Yes, I know Stag Arms makes lefty ARs, but they’re still just a hack on the existing design, rather than something easily workable for both lefties and righties.
There’s a lot of ways to improve the current situation:

  • Ambi magazines and ambi mag releases. See the Springfield XD for an example — instead of the notch on the magazine being on one side (such as on the AR), it’s on the front of the magazine. The mag release can be pressed from either side to disengage the catch. Smart design, with no aftermarket hack needed.
  • Ambi selectors as default. Many 1911s, even inexpensive ones, have ambi safeties. Is it that hard to adapt to other guns as a factory option?
  • Mirror image controls. Is it that difficult to put an ambi slide stop on a pistol? Not really. What about all the levers (like the decocker) on a Sig? They’re way at the back of the gun and only on the left side, and so are all but impossible to use while shooting left-handed. Would it be that difficult to mirror them on the right?
  • Swappable ejection on bullpups. Some bullpup rifles are all but impossible to shoot left-handed, as they’ll eject spent brass into the shooter’s neck. Ow. Sure, many bullpups are swappable, but quite a few aren’t.
  • Ambi-friendly military weapons. Having to swap out weapons in combat (e.g. replacing your weapon with that of a stricken comrade) can be a pain, particularly with bullpups. Sure, a bullpup’s ejection side can be swapped, but that takes a few minutes and usually involves partial disassembly and tools. This is a Bad Thing. Having the rifles eject brass downwards, forwards, or in some other safe direction would be better, and allow a bit more flexibility when SHTF.

I’d imagine it’s far easier to address such issues in the design phase than after a gun is in mass production.
Self-loading guns make it even easier, as there’s no control one must operate (like the bolt handle on a bolt-action rifle) to make the gun ready to fire again.
I could understand bolt-action rifles being made in left- and right-handed versions, but self-loading guns should be a lot more symmetrical, so as to cater to all different types of shooters.
/gets off soapbox