On newer Intamin coasters, the brakes retract below the track when the train is at the target speed. PlanCo has this feature in the brake design on some coasters like Zenith, Barghest and Infinite. However they don't retract into the ground which would be something realistic and cool. Also these retractable brakes on hydraulic launches should be added. Other people have suggested rollback probability and without the retracting brakes for hydraulic launches this wouldn't work as the train would suddenly stop in the station (with around 20 fear and nausea and infinitely high G-forces.)