They put it there because it's cheap. If it was perfect, there wouldn't be different engine calibrations for same engine+ecu combo every year.
Had another toy recently, another turbo engine with the E80 ECU and about 30'000 miles on the clock. Can't even keep the commanded boost within 0.1 bar on everything stock (Desired MAP vs actual on images below). Brand new car.
The wastegate DC table looks like somebody smashed the keyboard with a hammer and then left it like that. Oh and the default boost control PID setup likes to overshoot and oscillate whenever it feels like it.