Lets take a claim "a random chance could land you in jail". I've seen numbers that percent miscarriage of justice in US is about 5-10% (not sure it's correct, but anyway even for death penalty there are many mistakes http://en.wikipedia.org/wiki/Wrongful_execution). So for modern US 0.05% (about 160000 people) are in jail by random chance. I don't have numbers of USSR and, again, I am not trying to compare. I show that you should be very careful when using simple claims without numbers.
Or let take "simple political joke". Do you know that in many modern countries you can go to jail for ten years just for telling something that is not accepted by mainstream (http://en.wikipedia.org/wiki/Laws_against_Holocaust_denial#A...)? Again it's incorrect to compare. but I think raw numbers people in prison is quite accurate and objective estimate of "badness" of system. And for USSR in thirtieth numbers doesn't look very terrible.