Hi Sean (?),
If we're comparing Taurus 1911's with STI 1911's, I would agree there is a difference in fit but not a "huge" difference as you state. Both companies use a "custom shop" approach to manufacturing.
Taurus barrels, slides and frames on both the blued and stainless versions are Taurus-forged, not cast, and are individually hand-fitted to match-level tolerances during assembly. Some people claim forged components are superior in strength to ones that are cast.
STI slides and frames are either cast (e.g., Trojan) or forged (e.g., Legacy). To some people this makes a difference. Personally, I'm not fussed either way.
All parts on the Taurus PT 1911 are manufactured by Taurus, including the magazines and the custom-style accessories, and they are specific Taurus configurations and not copies of any other brand-name designs.
Even the Heinie sights on the guns are actually fabricated by Taurus, under license and according to Heinie’s specifications. Most of the small parts are manufactured through metal injection molding (MIM).
STI also uses MIM small parts that are fabricated by outside contractors to close tolerances.
I guess I'm saying that we have to get beyond thinking that just because something costs more it's got to be better.
The Taurus 1911 costs less than the STI 1911 because it's made "in-house" using "smart" manufacturing processes. Lower labour costs in Brazil also help to lower the cost of the product.
I own or have owned STI and Taurus pistols and I haven't had any problems with them. Both companies produce a very good product and appeal, as you say, to different market segments.