The problem is in most cases by the time you're talking about involving a lawyer, most consumers have given up the fight. A majority of the fraud cases I've had requiring charge backs have been in the 20-50 dollar range, so not nearly enough to justify legal assistance.

By putting the onus on the legal system it allows merchants to commit smaller scale fraud more easily because normal people don't have lawyers on hand and aren't willing to do so for a $30 case of fraud, as justified as it may be.