Brake fluid changes are definitely not an invented “cash cow”. They may BE a cash cow for some shops but changing fluid is important. Cars will not pass inspection in most EU countries without changing the brake fluid every 2, 3 or 4 years depending. There are tools to measure moisture content in brake fluid. You’d be surprised how much water gets in to your fluid. The meter tops out at just 4% which happens at just about the 4 year mark for many cars.
Americans have never been told they need to change brake fluid 'cause American carmakers never recommend it. If some do now, most never read their owners manuals… some of which say to change it, like the Acura Integra. Time is more important than mileage so waiting for a pad change may be too long for some.
So don’t change your fluid. It will get changed when you have to replace corroded, seized calipers or a leaky master cylinder (was that a seal or corrosion??) anyway.
BTW I wouldn’t let Pep Boys wash my windshield, let alone change brake fluid. Take it to an indie mechanic.