smoothness and nibs

So can someone explain to me how come all of my $2 disposable Pilot FPs
write so smoothly when new, while it's hit or miss with both generic
fountain pens and brand new pens from Parker, Sheaffer, Waterman? Some
of the latter skip, or go dry, or require more than a little care as
suggested by DA Book. Sometimes, even that won't turn a scratchy nib
into a useable writer. But ALL of the cheap Pilots (just tried out
half a dozen before giving them to my son) work. And unless I buy from
a reliable guy like Nathan, even my vintage pens are hit or miss.

I'm not asking for flex or special italic whizbang. I just want all
pens to flow well, lay down a dark line, and be very smooth whether
it's an EF or BB.

One random note: Hooray for Noodler's! I just got a few bottles of
Nathan's ink and it's made many borderline pens full scale users. And
one older cheapie pen ("German" iridium nib probably from China) now
writes like one of my very best, ultra-smooth, extra fine nibs. Just
think, one dealer told me that EF pens are "always" a bit scratchy.
Yeah, right...

I wish there were a local pen show so that I could commune with the
experts. Then again, the lack of such keeps me solvent.

Machine-made Pilot disposable vs. hand-made more-expensive pen.

There used to be a large number of expert nib grinders working at all
the good pen companies. Now the majority of them are either retired or
laid off, and the few nib grinders who are still on the job may be
overworked or inexperienced or both.

This is bad for the pen business in general, but good for independent
nib grinders and repair people, who I'm sure spend a lot of their time
fixing factory mistakes.

But I still don't get it. If machine made cheapie nibs are so good,
why can't one make cheap imitation "German iridium nibs" that are just
as good? There are lots of cheap but pretty pens (like those sold for
$10 on Ebay) I'd buy more of if there were some way to buy an
alternate nib. In fact, some cheapie pens I have bought have turned
out better than pricier ones. Look, Pilot can do it at the low end.
Why is it so much harder to do for a $20 or $200 pen?

I suspect the answer is that a machine-made nib is only as good as the
machine that was used to make it. A cheap or worn machine won't do the
job very well. I also suspect Pilot's engineers are pretty good at
their jobs. :-)

This is a common question, unfortunately one without a satisfactory
answer.

Ok. So a related question: Are there any nibs that can be substituted
into those generic German iridium nibs that are available?

Thx.