That means you can place the cue ball anywhere on the table you wish. And you can shoot the 8 ball into any pocket you wish. That means if the opponent scratches, it is almost a sure loss of game for the person scratching. Nine ball also uses the 'cue ball in-hand' rule. And the reason is because what you just complained about.
Players use a scratch to put the opponent in trouble.
It just doesn't apply anymore. Your opponent is using the rules to win but is not accepting a 'penalty' for the scratch. Remember that this rule applys to all players. Change the 'four' or the 'six' to a stripe. There 'must' be a solid and stripe in the rear corners - and it doesn't matter which corner.