How would your friend like to change the system? There have been, and are, countries where trials in absentia were the norm and where guilt was assumed rather than innocence. This is not to say that our system is the greatest: money has a greater influence that it should, prisons stats certainly show bias, as do the preponderance of police shootings and brutality incidents. Consider this though, you aren't subject to summary execution for possession of drugs, cannot be hit with a cane if you spit on the sidewalk or sentenced to hard labor in Siberia.
It's easy to say that something isn't "fair", whatever that means is very subjective, but how to create positive change that is more than superficial is the hard part.