I don't know how much clearer the ESRB could be. It has the general rating, the age group it suggests and on the back it gives a general outline of what kind of objectionable content the game contains.The Dutch version works great (both suggested age categories, and clear information on why: this one has bad language, this one refers to drugs, this one shows cartoon violence, this one has full-frontal nudity and penetration,...whatever). The American system isn't exactly as robust or as useful, but still. Things like GTA aren't rated "Great entertainment for toddlers".
By the sounds of it you want the ESRB ratings to be like Canadian cigarette packaging.