Alright, well obviously it's not something I would be doing myself. I'm not a licensed gun manufacturer, so I couldn't do it myself anyways. I was just making a point; couldn't it be done like that?
Yes it could, but it would be pricey. The place I know that could do it would probably charge you tens of thousands (as they get about $3K for a single 1911) if they would do it at all (and my guess is they wouldn't). The problem is there are a lot of parts that need to be made, and this involves more than just "reversing the X and Y". In some cases, specialized fixtures (made in-house) are used to set up the parts for machining, and setting up the machine used for each one takes time - and takes the machine out of production while that's done.
You're not talking about just a single program, but multiple programs for CNC machines, lathes, screw machines, EDM machines and even the barrel machine if you wanted a barrel with the twist reversed. For a true mirrored 1911, MANY parts would be inverted. It would be possible to increase the commonality with some design tweaks, but this would take even more engineering time.
And then there is the issue of spare parts. Let's assume you hire out to have a left hand 1911 (or other gun made), and some day, you find you need a left hand ejector or magazine release button. How much do you think it will cost to have the shop set up for a special run of the "you only" part?
You could look for an old Walther P5 which has the ejection port on the left, or an uncommon Falcon Portsider - but just spend a few minutes browsing the web to see just how available left handed slide stops, extractors and ejectors are for the portsider.
Alright, well obviously it's not something I would be doing myself. I'm not a licensed gun manufacturer, so I couldn't do it myself anyways.
Sure you could, for personal consumption only.