Thank you for the helpful information. My owners manual doesn't specify when they should be changed. The injector cleaner in the gas is a great idea. I took my car to a dealer to service the vehicle. They said my fuel injector needed flushing. Then they tried to sell me the entire package which includes flushing the brake fluid and the cooling system.
Brake fluid service -- industry standard for replacing the fluid is about 3 years. It is not mileage based, because it gets replaced for moisture build up in the fluid, which is not driving dependent.
Fuel injector service -- there's a fine line between "need" verses "recommend". I'm guessing it's "recommend" since you don't have a failure you are sharing with us.
I would suggest YES on the brake fluid exchange, and NO on the injector service - if you have no fuel system problems.