A scope with poor glare performance will also tend to have generally low contrast on bright days, especially when the sun is in front of the shooter. That's one reason target shooters don't notice glare and contrast problems. Most firing ranges face North and have covered firing lines. Typical paper targets have good contrast and get direct sunlight.
Many big game animals, on the other hand, tend to avoid direct sunlight and have natural camouflage. That means they usually have low contrast.
When you look through some scopes and the image seems to pop out at you, that's effect of high contrast. High contrast does not come easy or by luck. Zeiss, Swarovski and Kahles are examples of scopes that have been specifically engineered to have high contrast. Those manufactures have a culture that places a high priority on optical performance. They have the proper glare measurement equipment and know how to use it. They specify high surface figure lenses, low reflectivity internal finishes, glare stops, etc., to minimize glare.
Companies that focus on marketing and rely on other manufactures to design and build their scopes lack this expertise. Their scopes have good features, but lack high contrast. Vortex, Sightron and Weaver are examples.
Leupold, Bushnell and Burris fall in between. They started out building their own scopes and generally produce scopes of better than average contrast. They are at risk of loosing the secret sauce because more of their products are being made offshore. Nightforce is still producing scopes with above average contrast.
