As someone who knows emergency vets, you have no idea what you're talking about and this is incredibly offensive. Vets don't go into veterinary care to get rich. They get into it because they care deeply about animals.
If your dog is bleeding out or not breathing, nobody is going to sit there waiting for you to swipe your card; they're going to try to at least stabilize your dog, and then talk to you about diagnostic options and so on. Emergency vets charge an up-front diagnostic fee and anything that is not "your pet will die if we don't act right now" has to be pre-paid.
There are no government funded veterinary clinics.
There is no legal right to emergency medical care for pets.
There is no government agency guaranteeing the vet ER gets paid if the owner isn't able to, or simply refuses. Debt collectors typically pay out a fraction of any debt they agree to collect...assuming the ER can even identify them. ER vets can't put liens on your property like hospitals can.
Most pets are not insured, and frankly pet insurance is a ripoff. Lots of exclusions and a lightning-fast "prior condition" reaction is how they avoid payouts. It's not regulated because in America, we don't Do That Sort Of Thing (no step on business snek, as business snek regulated by free market!)
Emergency medical care for humans is the most expensive kind of medical care there is. For one species, one usually able to communicate at least on some level.
Now imagine all that, multiplied by multiple species. Equipment, a pharmacy, and staff able to care for patients of almost any size, multiple species, of wildly variable temperament, who have nearly no ability to communicate or participate in their care. And who have an evolutionary drive to hide injury and pain, usually.
Part of the reason ER vet care is so expensive is because they do not "demand you pay" while your pet bleeds out or sits there on the table not breathing...and when people inevitably don't pay (in part because they're people like you who shout "well my dog died anyway, why should I pay you!?"). That has to get amortized over all the people who do pay.
The vast majority of pets that end up in the ER are dogs, and the vast majority of those are in the ER from getting hit by cars, into fights with other dogs, or poisoned/obstructed by things they ate - most of the time because they were not on a leash.
What do you expect ER vets to do? Who pays to keep the lights on? The massive pharmacy stocked? The staff trained? The imaging equipment working?
The magical pretend emergency animal care fairy?