Yes! And this is the thing about insurance type products: most of the time you don't need them! And you can probably get by with not getting them most of your life.
But this time you needed it, and you opted out. You gambled and lost. You're out $300. Not bad for having a car delivered to you in the middle of night in the middle of nowhere, to be honest.
I travel a lot. I fly a lot. I have never bought travel insurance for my flights. I fly internationally a few times a year, and still I do not buy travel insurance. In my 20 years of adulthood, there have been two instances in which travel insurance would have come in handy for these international flights. One time I had food poisoning and another time I was finishing up a project and was out of time. First, worthy of noting that only the former is something that travel insurance would have covered. Poor judgment is not something that insurance usually protects.
But the point is that over the last 20 years, I've chosen not to buy several thousands of dollars of travel insurance. One time, if I had purchased the insurance, I would have been better off. As it was, I ended up buying a last-minute, EU-US ticket for $2200 in coach. That was my penalty.
This is your penalty. You opted out. When you called and said you had a flat tire in the middle of nowhere, they could have explained that you opted out and hung up. Instead, not knowing the exact conversation that you had -- and again, I'm pretty skeptical that they offered this service , in the middle of night, in the middle of nowhere, that you explicitly chose not to pay for, for free -- they somehow offered you salvation. For that, they charged you $300 and you're upset.
That's your penalty. Things turned out better than expected. If you ran a business and part of it was providing assistance at any time, day or night, for $20 a day...and a person chose not to avail themselves of your business....are you showing up in the middle of the night for free?
That isn't reasonable. This is your penalty. That is all.