Couple that with the additional traffic information they have to reel off prior to giving what should be a relatively simple take-off or landing clearance and you have a recipe for misunderstandings.
Which would only be made worse with ICAO one digit at a time call signs, such as Tenerife where KLM received a four number call sign, a new departure clearance with altitudes, fixes and radials......all in a single transmission with the words "cleared" and "takeoff" while he was assigned line up and wait.
Would a two or three digit flight number (or phraseology which compartmentalized it to such) have made the difference? Maybe not, but it would have made the odds better.
1705:53.4 APP KLM eight seven * zero five uh you are cleared to the Papa Beacon climb to and maintain flight level nine zero right turn after take-off proceed with heading zero four zero until intercepting the three two five radial from Las Palmas VOR.
Even the controller....one digit at a time and then "uh"