Often the photo evidence is unclear.
As long as someone admits to driving, pays the fine and accepts the points, the courts are not too fussed about it - unless they suspect someone is avoiding a tot-up ban.
You should plead guilty by letter - check out the details of the letter advising you of the offence - you don;t have to attend court.
Some police forces offer you a 'speed awareness' course if you haven't had one in the last three years - it costs £60, but you avoid the points, so check out if your local force offer it, and sign up. If they do, you'll be sent an offer to attend through the post in a few weeks.