OP clearly said, "... that CAN lock the wheel...", not, that *will* lock the wheel. The brakes should under all circumstances be able to provide enough torque on the wheels in order to stop the car, including being able to lock the wheels. How much of the ultimate stopping ability gets used, should be up to the driver or the ABS system. The failsafe on the ABS, by the way, should be (and as far as I know, this IS the case) that it cuts itself out of the loop and allows the driver to apply full hydraulic pressure to the brakes.
A problem with current driver ed is that people are still being taught to pump the brakes to prevent a skid. With ABS, this is counterproductive. Without ABS, it can help, but it's not as effective as threshold braking. The thing with pumping the brakes is that everytime you pump, you use some of the stored vacuum in the brake booster system. If you have the throttle wide open (as in a 'stuck accelerator' case) then the vacuum is not being replenished, and you probably have only one or two assisted stops worth of vacuum in the booster circuit, and the right thing to do is to get on the brakes HARD and then switch off the ignition, taking care not to click the key all the way through to where it locks the steering column. This is a technique that can easily be practiced in a wide open parking lot or driver's ed facility and it would save lives, or at the least some cars.
