I understand your argument, but part of this comparison is between Net profits and Revenue. While it cost Meta close to zero to have that ad space, it does cost meta money to run their platform. It is the same with any good old classified ads, or even free newspaper.

Meta dont actually dictate the value of ad space, they are largely market driven. Even though Meta may try to manipulate it to their advantage. Had they not been able to provide positive returns for those ads, they would not been able to continue and charge those price.

Also I think this is somewhat US specific. I dont know if that is still the case but US digital ads works really well. And they cost far higher than European or other part of the world.