Having finally given up any hope of a positive resolution, I'm posting online about my experience…read morebeing scammed at this Hertz location in the hopes that it will at least help steer others away from here.
Here's how it works. You make your reservation online (in our case, we were pleased to reserve an SUV for 15 days for under $800, which seemed like an amazing deal). I had read on various forums that we should book directly with a local company, but I ended up deciding that it was worth it to go with one of the bigger name companies in case anything went wrong. It was a mistake.
Once you show up to pick up your rental, one of two things happen. If you're lucky (like my Dad was, who was picking up at the same time as me), everything goes smoothly and you get your rental without any issue. If you're unlucky, they tell you that it is "illegal to rent a car without additional insurance" and tell you that you owe an additional $500+ on top of the $800 reservation, and that they will not give you a car unless you pay for this insurance.
Not sure how you end up in one category or the other. It may be luck of the draw - maybe my Dad just ended up with an honest person checking him in, while I randomly ended up with the scammer. More likely, they saw that I was exhausted from a long day of travel with three young children and correctly recognized that I wouldn't put up too much of a fight, and also wouldn't call their bluff and just go to another rental agency. From subsequently reading about this scam on message boards, it sounds like if you really stand your ground and fight back, they will eventually give up and let you have the car for the price you reserved it for, but it can sometimes take hours and I definitely didn't have the capacity for that. Also, if you're thinking "my credit card provides rental car coverage", that's not going to help you. They just tell you that you can't have the car without paying additional money. Pointing out that my father wasn't required to pay the additional fee didn't make any difference (and honestly we didn't want to push too hard on that because we were glad he wasn't a victim of the same scam!)
If this happens to you, you'll reach out immediately to Hertz customer service, but they will tell you there is nothing they can do until after the rental is completed, and to ask the Hertz staff about it when you drop the car off. You will follow instruction and ask the staff about the situation when you drop the car off. They will be very sympathetic and agree that what happened to you was wrong, but they will say they can't help you and you'll need to reach out to Hertz directly to resolve things.
So, you'll reach out to Hertz. If you're like me, you will spend 4-5 months speaking to dozens of different customer service representatives trying to get someone to understand and care, but it will ultimately be for naught. Most of these reps were very kind, but they all said the same thing: "We spoke to the location, they said you agreed to the extra insurance, so there is nothing we can do". The fact that I was aggressively forced into signing for this insurance under threat of having my rental taken away did not seem to matter to any of these people. If you're thinking "but I have status with Hertz, I'm sure it will be different for me", I regret to inform you that my President's Circle status made no difference in any of this.
So, five months after being scammed out of $500, I'm finally giving up and admitting defeat. My final act is to post my account of this experience on the internet in the hopes that it might save others from the same fate! I wish I had done more research in advance, as stories about this specific scam are all over the internet now that I know what to look for. I'm mostly disappointed in Hertz as a company for allowing this sort of thing to happen, and refusing to believe me or do anything to make things right despite literally dozens of emails that I've sent to different customer support members.