> and there's often in practice no penalty for violating them.
This is the crux of the matter. The laws are too weak. If the law said that that in addition to a refund there was a mandatory $100 compensatory payment due for every payment taken improperly (eg. every payment taken while unsubscription using the same method didn't work) then you'd have a few activist consumers waiting five years, recording the evidence and then demanding $6000. The problem would disappear overnight.
I wouldn't be so sure. E.g. EU mandated substantial compensations for delayed or cancelled flights. In practice the airlines typically just refuse to pay. You can contact an ombudsman that can sternly suggest that they pay, but not actually make them pay.
Of course you can take it to a court, wasting countless hours of time and risking tens of thousands in legal fees if you lose.
> wasting countless hours of time and risking tens of thousands in legal fees if you lose
That's a huge exaggeration. For example in the UK (not in the EU now I know, but roughly the same and I know the system better) you're looking at risking under £200. The loser will pay the fees. If you're certain that you're owed compensation under the law then there's little risk to take.
Source: https://www.moneysavingexpert.com/reclaim/small-claims-court...