15yrs I did as a copper, during that time I became more and more dis-illusioned, at the the end I took a career break moved to France & then told 'em thanks but no thanks!
I enjoyed the job for the main part. I hated the red tape, which keeps bobbys off of the street.....which is where most of them want to be..... I recall one night shift I had info' to give me enough to nick a bloke I'd been after for a job. I went out at 2200hrs and 'got him'. I booked him in at the nick & then went off to get a statement. Whilst returning I picked up a drink-driver. I got back into the nick with him around 0100hrs. I finished with him about 0300hrs & then dealt with the other bloke. Finishing about 0645hrs. I got back to my station around 0730hrs when shift ended at 0700hrs. Due to me being busy in custody that night my 'patch' which was something like 250 square miles was policed that night by my Sarge... on his todd.
So so often you hear on tele, read in the press & are told 'the police did nothing' or 'the police didnt prosecute' . Well if something is reported to the police it is recorded somewhere & has to be 'written off' in one form or another. Be that 'no further action' or 'person charged', it will be documented & authorised.
One thing people tend not to follow, is that police do not prosecute, that is the job of the CPS. Police will charge offenders. Hours of paperwork will be put to CPS & often CPS will decide due to 'lack of evidence' or other such reasons not persue the matter. The police are then left to inform the aggrieved, hence 'The Police did nothing' stories. With CPS, they very often find themselves trying to prosecute in a law court against the top barristers..... the money is in defending......... so all the good ones go that way!
One of my biggest bug bears was turning up in magistrates court to find 'my prosecutor' and asking him/her what he/she thought of the evidence, to be told, "oh I have'nt had chance to read the file yet". My reply after about the 5th time I heard that from different prosecutors was, "well you can bet your ass that the defence have inwardly digested it & will pick out every dot missed from an i and every cross missed from a t"
Don't get me wrong, like in all walks there are baddens out there. There are goodens to, but 'good police work' gets less readers to buy the papers than a 'bad cop' story.
Sorry if that was a bit of a 'rant'
To answer the OP's question:
Reporting a driver using mobile. Well, this comes down to your word against theirs if it was followed up. CPS woudn't run it. Same goes for careless driving and other 'minor' offences. Very often I asked people reporting such things, if they'd be willing to give evidence in court to be told, " your're joking mate your the copper you do it".