First, I agree that passively allowing this sort of crime to go unpunished is one huge factor in it becoming more common. When legislation, budgets, jail overcrowding, etc., ties the hands of police and courts, making prosecutions unlikely and sentencing light or non-existent for this sort of crime, it emboldens criminals.
Further, the hassle of taking the time off work or out of a busy schedule to appear in court likely means that a lot of victims don't bother doing their part in successfully prosecuting such crimes.
So the criminals know that the chances of being punished are slim.
But with regard to potential retaliation, and to play Devil's Advocate here: Something people need to realize is that the brains of most repeat offenders often do not work the way most of us would hope or imagine. We cannot put ourselves in their place and think through what their thought processes "should be".
Studies done on repeat offenders in prisons have shown that they often make the same logic and thinking errors over and over.
Often, they display sociopathic thinking. They do not see theft from someone else as a crime or even something wrong.
On the other hand, they may perceive any action against them by others as an unwarranted attack, even if it is a logical outgrowth of their own behavior (which, once again, seems perfectly normal to them).
Many of these people show lack of empathy toward others and an inability to accept any blame for their own bad actions. Nothing is ever their fault. They're the ultimate selfish, "entitled" citizens.
I should avoid making the obvious political remarks here, but I suspect many of you can already see where that might be going!
Anyhow, I agree that everyone needs to step up to the plate and do their duty and part as a member of our society, and within our system of justice to assure that it works.
But it is well to realize that we cannot expect criminals to think with the same logic that we would use in the same situations. After all, if they thought the way we do, they wouldn't be stealing packages off of porches to begin with.