The Tory Government would rather pay to put some stupid lines inside a box of chicken in a half-arsed attempt to be seen to be doing something to tackle knife crime rather than actually invest into deprived areas and poor neighbourhoods. You're giving them far too much credit. I do not believe anyone who has researched problems like this for decades could seriously come to the conclusion that this is a wise approach. The backlash to it alone already should tell you what a poorly thought out idea it is. And 'poorly thought out' is probably the most generous take I could give. Forget the "PC" aspect to it, which in itself is a symptom of the utter lack of serious thought behind this, it's just a total waste of money. A government message on a chicken box is not going to resonate with a disaffected youth living in an area rife with poverty.
No one thinks putting a message on a box is more effective than eliminating poverty, social deprivation and a lack of purpose, along with all of the other things we think lead to crime. Those things cost more money than we know and certainly more money than we have, when balanced up against all of the other nations' priorities. It's just one incredibly small tool used in a massive toolkit to tackle a problem that the entire human race still don't understand anywhere near well enough to solve.
The motivations behind doing it are different for a wide range of stakeholders. The tories were not the people who created and developed the idea. Nor were they the people who designed or executed the campaign. So yes you can believe it is a terrible idea but you can't believe the reason this happened is because this one group had this one motivation and this was the result. It is factually untrue. And the likelihood that all of them had that shared motivation is so small that it isn't even worth considering.
They are the ones who gave the green light and their motivations for doing so are undoubtedly largely driven by all of the terrible incentives in politics we know about, and fuelled by many of the in my view terrible attitudes towards society we agree they have. But you and others focusing solely on that one element - that one decision maker of many, that political enemy you're so accustomed to vilifying - is also driven by many of the terrible incentives in political thinking.
It might be a terrible idea but to believe you know it is because you understand the complex nature of how political messaging works on such a specific level is ludicrous, in my view. We don't even know how people form a thought. And there's all sorts of evidence that attitude changes can be influenced by seemingly ridiculous things, when lots of seemingly random events work together. Tieing this back to a political slogan and then saying this is why it happened and this is why it will fail...baffles me. But that is what happens in politics so it's just one obvious example of my own ignorance.