Because you dont actually understand what random is.

I didnt bring up police line ups that's someone else in this thread. Im just happy to point out how those are essentially random selection as well.

My original point was that the OP was ambiguous on the selection process used for the population. thusly assuming a random selection process from the overall popullation is just as valid as assuming 1 worm farmer + 9 randoms.

Now: randomness.

Given a random population of N entities, assume you want a sample of M where M < N and you decide to filter by Y to get X sample.

X is still random despite the filtering. all you've done is biased the N random population towards Y. but unless you remove the initial randomness (somehow... which is almost impossible btw). this is why so much of science is predicated on collecting large datasets because we have to make sure enough of the data has the attributes we want that it'll show up for study once we apply our faulty filtering mechanisms. and its why we spend so much effort creating better and better filters. its also why algorithm that leverage randomness are so powerful, because they match the reality of the problems being solved.

Using the line up as an example:

1. witness says the individual they saw had a long wide nose and a blue shirt.
2. reality: witness had a blue shirt.
3. reality: The detective has very different definition of what a wide/long nose is than the witness.

applying those two faulty filters to population N is still going to result in a random population because the initial candidate selection before applying those two (faulty) filters is random.