There is an old saying that a liberal is turned into a conservative by mugging. (Yes, I know that this is abuse of the terms "liberal" and "conservative", but for the purpose of this post you can replace them with "a person who advocates milder punishments" and a "person who advocated harsher punishments".)
There is a point in this saying, and I've even seen it demonstrated. Right after getting assaulted in the street by some teenage asshole a certain ex-boyfriend of mine said the exact same things that I tend to say after a cup of tea, and before that I was thinking that the man had never listened to me at all.
The funny thing is that you can turn a conservative into a liberal just as easily. Just mention a crime - any kind of crime - that he or she is likely to commit, and you'll hear the liberal rhetoric that Amnesty International would be proud of.
People often wonder why we don't have harsher punishments for various crimes and infractions. I think that the obvious answer is that because we, collectively, don't really want to. (Well, actually to be honest the current situation in Finland is such that I think we for once do want to establish somewhat harsher punishments, and we probably will, but not nearly to the extent that many people like to advocate.)
Quite a lot of people like to advocate really harsh punishments for the kind of infractions they themselves are unlikely to commit. It's fun to watch them squirm when you suggest the same for their favorite crime, be it speeding, smoking pot, incitement against some population groups, saying naughty things about the unmentionable child-loving prophet, downloading copyright-protected stuff, etc. Suddenly all the "the rules are for everyone" and "people should obey the law" and "don't want to do the time, don't do the crime" turn into "please be reasonable" and "overly harsh punishment for such minor infractions is counterproductive", and "but I think this shouldn't be illegal!" Well, guess what: your friendly local drug dealer thinks that shouldn't be illegal, either.
I wouldn't go as far to say "we are all guilty", but with the number of various punishments being about 10% of the number of the total population, and most of us even not getting caught for whatever it is we are doing, quite a lot of us actually are. And most of those who are not know somebody who is. And the really harsh punishment is of course meant for the bad guy who stole our bicycle, not our cousin who also stole one, especially what with the cousin having been caught and the bicycle returned and no harm having been done, really.
Not that I think that advocating harsh punishments for a certain subset of crimes is a totally untenable position. It is quite understandable to want to punish the really outrageous crimes harshly. One does, however, have to keep the punishments in some sort of a proportion (some legislatures fail it, but one should at least try), and quite a lot of "conservatives" advocate very harsh punishments for all the crimes that they are unlikely to commit. Because, you know, when your neighbor smokes a bit of pot he is a terrible drug fiend who should be locked away forever, but when you say that all the gay people should be also locked away somewhere you are not really hurting anyone, and besides saying so shouldn't be illegal anyway. Or the other way around. (The examples above can be replaced by any other examples of crimes that people commit often, and without much thinking.)
"All the people should obey all the laws or face really severe punishment" is a position that is quite easy to argue, but I've never seen any real live person actually hold it when push comes to shove.