Generally speaking, people fear capture more than they do punishment. Lots of incidents over the years support this, really. Once there is little or no perceived risk of being caught many people seem happy to try their hand at crime. Examples including the 2011 August Riots (which was just opportunism for the most part), or the mass violation of parking rules in some villiage once it became known that the sole parking attendant was suspended for the day, and so on and on and on. Even, for that matter, what goes on daily on motorways, where virtually everyone breaks the 70mph limit until a police car shows up, when suddenly they all become law-abiding drivers. And, once the police disappear, speed up again.
Increasing the detection and capture rates is the best way to discourage crime. Harsher punishments don't matter much if there's little chance of them ever being enforced.