For years at Towers you were able to use the turnstiles for Annual Passes, but this was stopped a year or two ago due to the problems of abuse. They seemed to go through several phases with the system over the last 2 years.
At one time when you scanned you pass at a turnstile some people had their photo and name bought up on the screen, presumably so staff could see at a glance wether the person scanning was the passholder. However, this never seemed to be rolled out across the whole pass scheme, and only ever happened to certain users.
There was talk once upon a time of adding additional screens on the back of the units facing the welcome staff so that it was easier to see. If you ask me, this would have been an ideal solution. A screen with your photo, name, and pass expiry date. It would allow everyone to use the turnstiles, whilst also keeping staff informed on passes. They could perhaps even have included some sort of audio cue, to alert them to a pass being scanned (Self service tills at supermarkets for example make several different subtle sounds to keep staff informed of what's going on).
I think it was last year when they locked down the turnstiles and forced pass holders to use the side gates (Originally the far left one had a sign advertising it as a dedicated Pass Holder Entrance). It was only recently this season that they reverted back to using the turnstiles, and clearly it's only been another short stint as they've since reverted back.
A long term fix needs to be found really, but in an ideal world I think that the whole plaza area needs a re-think to improve the flow of guests into the park. At times it can become quite a free-for-all, with long queues at the turnstiles. I think the issue is that once guests leave the ticketing booths they can move all over the place, either hanging back and creating bottle-necks, or just all merging into one scrum trying to get through any open gates. It would be good if there was perhaps some Tensa fences they put out in the mornings to channel people from the windows into the nearest set of gates, just to make it a little more controlled and flowing.
I also don't rate the barcode readers on the current turnstiles either. They can be very hit and miss as to wether they read, and often the ticket/pass needs waving around a lot to make it work. It least with the older Skidata units like Pleasure Beach have the ticket is put in a slot, ensuring it's always at the correct focus point to be read quickly.