Well Op I am going to bless you with an Evil answer... A very evil answer...
I love to write stories and I have been trying to write good stories that sell...
Sounds like a good excuse.... Yeah I go with I am writing stories thing...
One of the character thing I have noticed in most stories is A dumb villain... It always makes me angry when I see this
So with out further ado... An Evil Lord Under Answer
"So You are curious as to why so many people are missing?"


"Now for those that go poof I cant account for... but for the others..."
"First my army would not build itself... Recruiting leaves a problem.... You risk a chance of traitors and infiltrators... Their is a mathematically
determined limit of the number of people you can trust to run and operate an organization. Once you go past that you run the risk of exposure....
"
"Still not catching it... agh.... Ok..."
Taking a deep breathe," I will explain further... You see with a control staff of a small number of people who are under that number... I mentioned
it earlier..."
"Pay attention... Now why would you still men and women.... The answer is soldiers... But the parents are not the ones who will partake in the foot
work...
Using tissue storage
Brain washing
artificial insemination
dietary controls
Training
Female wombs
life support systems
I can create and control a core group of officers....
As for the grunts....
You can continually create new strains for new purposes....
Cybernetic chips...
breeding
Drug enhancement systems
Chemical delivery systems (human bodies, surgical ports for ex.... electronic pumps...)
You can design soldiers for just about anything.... They can be programed and be unbeatable.....
The continued disappearances is to improve the stock available... The reason is there are a few things that are outside science reach... the human
genome has a few more surprises in it then you know of.... So you need a fresh batch to increase your herds stability.... (please note this does work
with my own theory of human evolution)
In about the space of twenty years with no interference you can have at least four herds of about 250,000 a piece... whats lovely is that you can let
them out to graze to... they cant escape the prison of the mind....
So you see you can use all those who are missing to create a breeding program... all the prerequisite tech is available at the local stores....
Tractor supply, walmart, lowes, home depot, and radio shack...."
As to the question of disappearing right in front of others... the most logical is that the experiments on teleportation have began... Using some
theories in quantum physics ... the poofs are side effects....
Or Time travel post change reorganization... ( the particle waves realignment to match the present world)
I know the last two sound hockey but hey science is a religion too... and should not have that held against it....

The theories are for those that disappear in front of reliable eye witnesses......
To sum it up for you...
the op was right to ask... it was an intellectual exercise in the first part...
Why are so many people disappearing
Then it had a branch off
Well some have disappeared directly in front of others...
My belief is that the first general question easily explained... The government is probably practicing eugenics.... easy way to hide it and makes
those who are the bottom level contribute (please dont be idioso and assume this is my opinion... governments mindset not mine)
the next is harder to explain and needs a lot more evidence... my solutions need testing to find out if they are close to truth...