Why Do Allergy Shots Reduce Symptoms, But Not Being Constantly Exposed To Another Type Of Allergen?

First of all I’m taking allergy shots, but I’m confused because it doesn’t make sense to me that injecting an allergen can make your body more immune to an allergen whereas constant exposure to allergens (non shot-related) does not seem to be helpful at all. I’ve heard people say that their pet allergies “went away” [...]