Re: "He was found not guilty, therefore he is innocent"
The concept is there, but it's not simple. Sometimes a pattern of lesser offences is significant, but it isn't easy to present them to a jury as evidence. It will be argued about in each case where it comes up. And sometimes it gets argued several times, in different courts. In this case, this is the first step of such a chain of arguments.
Anyway, I knew a few magistrates. Apart from anything else, the police were known to have a list of favourite magistrates. I could see why. Some could have been more sceptical.