Yes, EvianBaby is quite correct.
Many road "accidents" do result in prosecution of one or more of the parties involved. Those prosecutions cannot succeed if precise details of the incident are not gathered at the time of the event. Some of the prosecutions are for serious offences which result in lengthy periods of custody and some of the civil litigation that often follows can involve tens of thousands of pounds in compo. For these matters to be dealt with fairly all the details must be available.
Your description of the M62 is a little flippant:
and it wasn't even life threatening, [how do you know?] it was only a shunt, a motor cyclist taken to hospital but he was fine, [how do you know] that's it.
Very often what seem to be trivial injuries turn into something much more serious. Some of the driving I have witnessed, especially on motorways, is downright criminal and warrants severe punishment and it's a pity that it is usually only detected when a collision occurs.
Ys, it's certainly a bind when you're held up seemingly for nothing, but it is usually necessary in order that the facts are properly established.