I'm 65 years old and been driving since I was about 14. I have put over 200k miles on several cars and guess how many times I've changed my brake fluid? Once, and I'm not sure I needed to that time.
I've never had a brake failure due to bad brake fluid.
If I have a mechanic tell me I should change my brake fluid every 50K, I would find a new mechanic.
You can't argue with science, Brake Fluid is Hygroscopic (which means it absorbs water, even out of the atmosphere, which has water vapor.) You can argue the simple "I didn't die, so its okay" excuse, but that's no different than a drunkard saying "I didn't get into an accident before when I was tanked, so I'm good to drink and drive."
While most modern braking systems will probably not experience brake fluid boiling, you have ABS Solenoid Packs and other systems in modern vehicles that will not like that extra moisture in the fluid. Almost every automotive training institution be it Toyota, GM, Wyotech, ect. all teach the same thing about brake fluid; it absorbs water, becomes contaminated, and can cause damage to the braking system and should be regularly serviced (some say 2yr/24k, others say 3yr/30k) So either everyone is conspiring against you, or there's a reason everyone is wasting their time trying to teach people to repair vehicles the proper way.
I'm sorry if I sound a bit rude/cynical; I'm not trying to attack you directly. But times change, technology improves, knowledge improves, ect. Thirty some odd years ago it was okay for people to throw Asbestos Dust around, because it "didn't hurt nothing" and no one knew better. A couple decades ago you could throw whatever engine oil you wanted in a vehicle and it wouldn't screw up the cylinder deactivation, or mess with the VVTi system, and/or cause any other myriad of issues that could potentially result in catastrophic engine failure.
My point is that while sure you've gotten away with not taking proper care of your vehicle like many other people in the world, it doesn't make it the right thing; nor does it mean that skipping maintenance is okay. There's a reason everyone goes through the trouble of teaching and learning how to work on vehicles; its not to take money out of your wallet, its because you can't just pop some spark plugs in a car, clean the points, and tweak the carburetor with your trusty screwdriver and call it a "tune-up" anymore. For better or for worse, automotive technology has become far more complicated a field and as such, so has the technology and knowledge needed to repair these vehicles. Which also means having to teach customers what taking care of your vehicle entitles and why things like using the correct coolant, transmission fluid, engine oil, and other parts are critical to maintaining your vehicle properly.
~ASE Website link going mildly into depth about importance of regular maintenance:
https://www.ase.com/News-Events/Publications/Car-Care-Articles/Protect-Your-Auto-Investment.aspx
Post Note-
In regards to the pricing for the brake service, you need to keep in mind that you are also paying for labor as well. This is typically broken down as a flat rate, most shops in our area seem to have the same flat rate quote for brakes. For example at our dealership it would be broken down as such:
-Front Axle Brake Service (Replace Pads, Clean/Lube Hardware, Surface Rotors) [2.0hrs for non-floating axle]
-Rear Axle Brake Service (Replace Pads, Clean/Lube Hardware, Surface Rotors, Adjust Parking Brake) [2.0hrs for non-floating axle]
-Brake Fluid Flush Service (with DOT3 Brake Fluid per vehicle specifications) [.8hrs]
So whatever the shops labor rate is, there's at least 4.8hrs of work being billed out. I'm just pointing this out because, while you can do the work yourself; you are going to a shop who has to pay overhead, the technicians, waste fees, ect. so the labor costs do factor into why its only $120 for the pads and $480 for the labor (these numbers are just for example.)
