The piers aren't publicly owned, they are private property. Tynemouth and South Shields are owned by the Port of Tyne Authority and Seaham piers by the Seaham Harbour Dock Company.
In the case of Seaham there is a long standing agreement between the club and the dock company for members to fish the pier and IIRC the club pays the dock company a substantial amount of money for the privilege, they are paying that money to a private company in order to get access to their private property.
Nobody who doesn't want to pay / be a member of a club with access rights is being prevented from taking part in their chosen hobby, there are hundreds of miles of beaches and rock edges on the north east coast that are completely free for public access and provide excellent fishing.