The short answer? Because both Taurus and S&W management are idiots.
Sound harsh? Sorry, but this is one symptom of a massive pattern of stupidity that would make Dilbert's boss blush.
Right now the gunmakers think they sell guns. WRONG. They sell parts of a complete self defense system.
IF THE OTHER PARTS DON'T EXIST, THEIR PART WON'T SELL.
But they can't see it.
The computer biz figured this out by at least 1984 or so, when Apple fought like hell to make sure apps were available for the Macintosh the instant it shipped.
Right now, if you buy an autoloader pistol you have to select rounds likely to work and test at least 200. That's utter madness - a recipe for "fear, uncertainty and doubt", the "FUD factor" that kills sales dead on arrival. Why don't the gunmakers get together with ammo houses and make sure there are solid loads available tuned for each gun they sell, complete with joint marketing? Why don' they make sure there are speedloaders and speed strips and holsters IMMEDIATELY available for every gun they sell, on the date of introduction, shipped to the stores?
Because they're fools.