Why paint the ambulance and not simply change vehicle ???
Why didn't the two brothers simply leave the ambulance and drive off in a car that the chicanos would have brought them??
Just wait thirty seconds until the helicopters / cop cars chase the 6 ambulances, change clothes, have one of the two brothers hide in the trunk (since the cops were looking for a black and white guys duo) and drive away, no? To me this is such a huge stupidity in the script.