Is all the cameras in the UK effective in any way? I mean, to know that the criminal wore a black hoodie and black pants at the time of the crime doesn't give m

Is all the cameras in the UK effective in any way? I mean, to know that the criminal wore a black hoodie and black pants at the time of the crime doesn't give more information than maybe sex, hoodie, pants and maybe a rough estimation of age. Is it a potent law-tool for Londoners? What was the reasoning for getting so very many? How do people generally feel about them?