If you have never seen a seizure before, it is a really scary thing. My sister is epileptic, but it didn't onset until her mid 20's. The first time I saw one, it was probably one of the scariest things I had ever seen. So even if they did know of her situation, I am sure they still felt calling 911 was the best thing to do.
As for the cost of the ambulance ride, they too are way to expensive. They charge you for all the equipment on the truck, not just what was used. But I know in my sister's case, both the hospital and ER allowed for payment plans. I also know that often the insurance company or the ambulance biller will code things differently so you should call to make sure they were done correctly. Example is my wife is expecting, and had some routine tests done. The medical biller coded it as "additional blood panels" category, which we do not have, when we called, they re-coded it as "routine prenatal" and got it covered as expected. It could be as simple a clerical mistake.
As for government mandated insurance, making everyone buy insurance I don't agree with, forcing the insurance company to allow people like my sister to get insurance in the first place, I support, even at the cost of making everyone else have to buy insurance. because of her epilepsy, it is considered a pre-existing condition, and since she is also self employed, she does not qualify for a group purchase, and has to go to a high-risk insurance company. Her monthly premium is 1500 a month, which thankfully they can afford, but I can't imagine a lot of people who can do that on top of normal living expenses, families, etc.
My former boss also had a son who was born autistic and was generally denied insurance from all the major carriers because it was a pre-existing condition. So the meds he was on had to be out of pocket. So you will be paying for them soon too.