In America plasma donation is paid and the harvest locations are typically located in areas with a large population of people who need supplemental income.
Paid plasma, even in America, isn’t used in transfusions because it is frequently contaminated with various diseases, precisely because you can’t trust people with a paid motive to be honest in the health screening.
You can’t even trust them to be honest for their own health. People lie to donate at different clinics to avoid the wait period, which is a pretty big problem because the American wait period for plasma selling is already too low to be healthy.
The plasma from paid clinics is used in various manufacturing uses, anything from makeup to products for haemophiliacs, but even after processing and extensive testing there’s still a significant risk of infection.