Sure, we can all agree that's how nature is. But that doesn't make it a good thing. Handicapped people would starve to death in a "natural" mesolithic world, but we generally don't want that to happen now.
If you want to protect biologically unintelligent people (<85 IQ), the poor, those ignorant of the law and court legalities, the confused elderly, or anyone else you think doesn't have the ability to have a fair trial, then you kick up your money and pay for it. Donate money to foundations that provide quality legal assistance pro bono to the "disenfranchised."