They tried honestly but there were great variations in quite a few 19th-Century guns, even some of the ones coming from factories which were state-of-the-art. It's just the state of the art wasn't quite as high as what they were hoping.
I have a Martini-Henry Mark IV (very end of production) with a bore that is .004" over, at least: you can pop a fired .303 case into the muzzle. Also have a '58 Remington with a bore the size of a sewer-pipe... "correct" .44 slugs fall right through it, gaining speed all the way.
They tried, and they ended up giving us the world we have today with the technology that's a part of it.... but all they could do, really, was try. Let's be kind and say that their aspirations were higher than their accomplishments.
That said, real soft lead and hollow bases both are real, common-sense 19th-Century ideas, ones that WORK.