If the police actually aren't on the public's side why should the public feel that they are?
The problem is not who's "side" they are on, but the definition of "the public". There is no single such entity (any more than there is any single "community"). Whilst we fail to understand that fact we will
always end up with claims that "the police are not on
our side".
Politics works on the majority basis (in theory) - i.e. the policies our society pursues are those supported by the majority of citizens.
Policing has tended to do the same ... but that has run into very obvious and justifiable concerns expressed by minority groups - to the effect that the police, on "the side of" the majority, victimise them.
This has been something that the police have struggled with for years and have still not got right ... but it is also something that has not been acknowledged as an issue by politicians and others (like you) who still talk in terms of the policing needing to be on their side, or on the side of some group they claim to represent ("hard working families", etc.).
The police simply cannot
ever be on the side of everyone - it is not possible. In the context of protest, your demonstrator is the bankers thug. In the context of the use of streets, your freedom to party is your elderly neighbours anti-social behaviour, etc., etc.).
The police should therefore not be on
anyone's "side". They should be entirely neutral and seek to enforce the law without fear of favour. They should provide a safe and stable society in which people are free to carry out any lawful activity in a way which does not unreasonably impinge on the freedoms of others not interested in that activity.
To enable them to do that
everyone (especially members of minority groups) should engage in the policing debate to ensure that the police have a sound and accurate understanding of their point of view and the issues affecting them. If they do not, they cannot legitimately whinge that their views have not been considered.