When an individual is the victim of medical malpractice or medical negligence by a company, a hospital, or a medical professional, the victim is put into an immensely difficult situation. Already struggling to recover from the harm, they must now prove their case using evidence held by the very people who harmed them; the ones with the most to gain from hiding that evidence. This is why the country needs lawyers, even if you don't want one living next door to you.
A great example from outside the world of medical malpractice is the General Motors debacle involving a faulty ignition switch. The news attention has been focused on the fact that GM knew there was an issue with the ignition switch but actively covered it up leading to some fatal consequences for consumers. The cover-up was only discovered after the family of one of the victims hired a trial lawyer to help them look into what had happened.