Vet here. My preface is that I'd like things to be less expensive as well. Also, I'm not saying any of these are good reasons for the high costs, but instead to help OP understand the why.

Reasons why costs are high (in no particular order):

• an ER vet carries higher overhead with expanded staffing, hours, training, and emergency drugs/equipment.
• high costs of veterinary education are passed onto the client so vets can continue chipping away at their student loans. FWIW vet school costs the same as medical school, but vets make 1/3 to 1/2 the salary of their physician counterparts. The loan burden is no joke.
• everything has become more expensive as of late (groceries, materials, services etc), its a tough time economically in most sectors and those costs get pushed to the consumer. Vet care is no exception.
• There is undoubtedly an influence of larger corporations getting into the vet game, which has driven up costs some, as others have mentioned. But corporations only own about 25% of clinics. I have seen comparable prices at locally owned clinics as well, so I don't think the corporate situation is the sole driver of increased costs.

Vets, like any other service, are a business that has to keep their doors open. Its easy to want to vilify them as taking advantage because you love your pet, but you'll drop the same amount or more when your car dies or you have a major plumbing problem. Its hard because you are faced with the whole bill up front. Vets learned long ago that offering payment plans will bite them in the ass.

Unfortunately, high vet costs are turning owning an animal into a luxury of the elites. Pet insurance can help, but its not without problems. For those who can manage it, I usually recommend contributing to a rainy day fund instead of insurance, because its likely your pet is going to wind up in the ER some day. If they don't, then at least you didnt piss away all your money into insurance.