I might be exaggerating here, but especially with a chain like Merlin, that never charges gate prices and gives away season passes, wouldn't the park already earn more with a single sold coke, compared to the admission price? I don't get it how with an area as huge as Alton Towers, which opens up plenty of opportunities for worthwhile, expensive pastime activities (what happened to the rope course btw?) and actual (like ACTUAL) restaurants, they literally have zero desire to make the people come at lunchtime, have them eat in the park first, then let everybody have fun until dinner which is also served in the park, finish the day off with a final ride at 8:30 and then everybody is happy? Like, when I go to any decent park with proper opening times (so Efteling, Phantasia, Europa Park) you'll see me show up at 11:30, head towards my favourite restaurant, and then gladly stay until 8 or 9 pm. That's plenty of money spent every single visit, which is especially valuable for these parks since I have season passes, so they are pretty much dependant on me doing that if they want to earn any money on my visit.
Ruining your guests admission price tolerance is especially harmful in that scenario imo, because as soon as everybody expects to get in for a dime, free season pass included, all your chances at selling "premium tickets" which include for example dinner, a coffee + pastry and a single fasttrack are already out of the window. Efteling has an offer like that and I would recommend that to everybody who doesn't have an annual pass.