This may come out as a 'double refund', but in generally accepted practice, paying triple of the dishonestly earned amount is also often considered an reasonable measure just as a penalty.
Otherwise if half of the cheated consumers complain and get their money back, and half don't notice it, then it's still a net win for a shady company and an incentive to continue such activities, contrary to the explicit goal of this legislation.
The law provides better protections to consumers, but it also provides some protections to retailers against some of the dodgy practices they've had to deal with from consumers. Returns and expenses are a HUGE part of the law.
My favourite bit is what I call the "anti-wardrobing provision". Under the new law, when you return an item, retailers can now deduct a fair percentage of its cash value from your refund if you have returned it clearly damaged or un-resellable. This is because of wardrobing - the practice of buying an item of clothing, deliberately keeping the tags on, wearing it once, and returning it for a refund stinking of your night out.
Because nearly always the trader/seller has more power than the little guy. It's good to 'encourage' them to not break the law in the first place.
It's like punitive damages.
This is encouraging the consumer to engage in self-help and gives them (in theory) just enough of them the motivation to keep on the lookout for the scam.
It's not the only way to run a regulatory regime, and it has some downsides, but it also has a measure of appeal.