Yes absolutely, you have the problem in a nutshell.

Unfortunately we have an ever increasingly politicised police forces who are happier being seen to have done something rather than doing something that works.

It is so easy to blame knives and guns than deal with the real causes, which are difficult, messy, take time and are costly.

To answer your question, it ends when the police (and politicians) are held to account. I can't see the Metropolitan police with their corruption and incompetency lasting much longer before they are taken in hand, disbanded and reformed. Perhaps the incoming Mayor of London will do it?

It is interesting that Scotland with the wind of change blowing through (another subject, another day) have recently combined ALL of their police forces, including the Transport Police, a totally different organisation, into one 'Police Scotland'. Early days but worth watching.