Insurance companies are in business to make money, not to help you. The contract you have with them says they have to help you when you mess up. They want to know if you are likely to mess up, and they can predict your risk in many ways, like where you live. What if the insurance companies could invade your privacy to know more about your risk? If they could monitor your driving at all times in order to come up with a rate, then you'd pay based on how well you drive, not just on the zip code where your car is parked and how many accidents an average person like you gets into.
With Progressive, you have the option of asking for invasive technology to be your big brother in the backseat. You ask for it with the hopes it will save you some money. Progressive gets a detailed profile for you and others they deem to be like you. Lots and lots of data. Months of beeping to let you know you're being watched and when you hit the brakes too hard. Actually, it kind of sucks, but Lisa and I will be getting a discount in the end by driving like grandmas and starmen.
In the movie Starman, when the title character (from outerspace) learned to drive, he realized that a green light meant go, a red light meant stop, and a yellow light meant go very fast. Progressive's Snapshot expects you to use this mentality, since it beeps at you for braking hard. My wife has always been a stickler for the rules, so she tends to slam on the brakes a bit more when a light turns yellow. I have always wanted to beat the yellow, so I have fewer hard brakes than she earns each week. She brakes hard about once every 25 miles in her car. I hear the beeps about once every 75 miles. She's a B and I'm a B+. Both of us are doing well enough to lower our rates, and hard braking is not the only factor.
I probably lose some points with my acceleration. If you've ever had a SAAB 9-5 with 3.0 turbo, you know what I mean: it's just fun to drive, even if it's not a sports car. She has a Lincoln that's fast enough, but certainly does not have a Sport setting or a little turbo meter on the dash. Basically, she drives like an old lady and then brakes a lot. I drive like a teenager (some of the time) and then run yellow lights. She gets a B and I get a B+. When I had a Chevy Cobalt Base without turbo or even ABS brakes, I earned an A because I could barely accelerate and never slammed on the brakes for any reason. My wife's car with stability control and my car with at least traction control, both with ABS, are much safer than the Chevy, but that's part of the point here. Drive an old Buick like an old lady and you'll win the Snapshot race.
If you get the device and see that you're on pace to brake hard more than every 20 miles driven, race off the line, and drive a lot after midnight, then I'd send it back before the 45 day point of no return. If you don't like the invasion of privacy, don't sign up and wait for self-driving, wifi-enabled cars that will know even more about you. If you think you're a good driver, then go ahead and get your discount. My Cobalt discount in Wisconsin was pretty good, but they would not carry it over to a new state.