This covers the trials not being fully representative, but largely neglects why that is the case.
The paper defines a population "at high risk of drug-induced serious adverse events", which presumably means they're also the most likely people to be harmed or killed by the drug trial itself.
Also, if they're known to be at such a high risk of adverse events, would they even be given the treatments, trial or not?
A lot of companies essentially cherry pick healthy patients and write insane inclusion/exclusion criteria to rule out anyone except for the ideal participant, which is why more and more research sites are negotiating payment up front for pre-screening and higher screenfail % reimbursement for into their study budgets.
Study design is sometimes optimized so only the "best" most enticing participants will actually be eligible, I've seen as low as 2% - 12% but frequently 50% randomization rates. Some studies also have 100 to 150 day screening period, a limited AND full screening period, etc.
Overly restrictive inclusion/exclusion criteria to super narrowly defined ideal populations hinders enrollment, causes a large burden to sites for prescreening and ends with trial results that fail to reflect real-world demographics.