Having stood by while one of these RAC checks is done, i'd say it's worthless.
Car was in showroom. Dealership manager had a word with RAC man.
Said they had 'prepped' the car and didn't really want to move it.
RAC man walked round car, sat inside, completed paperwork and left.
Now i'm not saying this is typical, but having seen this,
in my mind an RAC check is now logged as purely a paperwork exercise.
Could go some way to explain your problem though