This is the most misinformed unknowing take in all of the comments.

You can’t just recruit “200 homeless” and have it pass research standards. The homeless population is the most difficult of all to track, maintain accurate records, and even recruit for that matter. You think the homeless just line up for novel drug trials and report back for updates on a strict schedule?

You need good candidates for the trial. You need them to follow up. You need admins to properly track them and ensure it’s at least mostly accurate. Even the best trial candidates won’t follow the protocol correctly.

I invite you to read https://www.researchgate.net/profile/Carl-Elliott/publicatio...

If you genuinely think the medical and pharma industry don't exploit homeless and other marginalized populations out the wazoo as lab rats. They also only stopped doing it to prisioners when it was made illegal, because that's what they did before. Of course using them has a lot of practical problems, as you outline, other than the much bigger ethical issue.

You managed to miss the whole point of the comment though.

Which is, how is it possible that a multibillion dollar industry, exploiting both the test subjects AS WELL as the researchers in the form of practically free PhD candidates can still claim it's one of the most dificult / expensive endeavours? Where does the money go? When you look, it goes to the bureocrats and to the "bio-investors".

I (not homeless!) was recently in a vaccine trial (Moderna's mRNA vaccine for RSV). The trial paid me $100 per office visit, just to show up. There were periodic phone checkups ($50) and a weekly status check through an app ($10). I did follow the protocol pretty damn well. There was an incentive to come in and get checked when symptoms occurred, including when I came down with COVID at one point after a trip to Europe.