Teams do not adjust brakes from the steering wheel because the rules ban any electronic controls in the brake system whatsoever. This is done in an attempt to eliminate the possibility of an illegal ABS system being implemented.
It's not on the wheel, it's a mechanical lever down by their legs.
...like Ferrari since that's who they stole it from...
I don't understand how people always insert the pro/anti bias into things where it is not necessary nor correct.
It is correct, it was proven by FIA, and admitted by McLaren. I was not trying to change the subject, just point out that it's no surprise it was the same as Ferrari's 3-position system, since it was originally copied from theirs.
Back in '07 commentators kept observing the Ferrari drivers reaching down and moving something just before certain corners, it was surmised to be a brake balance lever, later confirmed during the investigation into the '08 McLaren where it was found on the McLaren, and it was revealed that Coughlan had obtained the design from Stepney and then called a meeting where he put it up and called it "the brake balance system of the future". It was one of 4 points in the FIA's report on the '08 McLaren, where Ferrari technology was found on the McLaren. Before that, the public didn't really know for sure what it was. Ferrari allowed it to remain, after McLaren volunteered not to develop it any further (that year).
In this example: Adjustable brake bias is as old as formula cars. I know of touring cars with preset 3 and 5 position bias setups that were common in the early 80's and I'd bet they were around long before that. To say that one team stole and idea from another when its been in common use for decades is a frivolous accusation.
It's not brake bias in general, but the real-time driver-adjustable system that resets automatically, that was an innovation in '07 and adopted by others in '08. The way it works is the driver knows which corners will need a more forward or more rearward bias from the 'normal' setting. Just before the braking zone, they move the lever forward or back, or leave it alone. Whether or not anyone else had something like that before in F1, I don't know, but the Ferrari innovation was that the lever automatically springs back to the middle position after braking, so the driver doesn't have to take his hands off the wheel and move it back.
FIA said McLaren also had some kind of "quite innovative" brake balance system of their own, but it was not like Ferrari's. After they saw the designs of Ferrari's, they threw out their own and copied it for their next car.