In some cases the fakes are downright dangerous. This is much more the case in supplements, cosmetics, food, and occasionally electrical appliances.
People will only sue them when they get actually dangerous products. Even then it’s a difficult process.
"As an example, if I sell Duracell C batteries on Amazon through their “Shipping Fulfilled by Amazon” — which I must do to receive Prime shipping designation — I need to send my batteries to an Amazon warehouse. After receiving my delivery, they will count the number of batteries, then slide the whole stock into a generic shelf labeled “Duracell C Batteries.” Any purchaser receives a Duracell C battery from that box, and thus the actual seller is unknown."
1: https://thetriplehelix.medium.com/your-amazon-products-could...
https://www.redpoints.com/blog/amazon-commingled-inventory-m...
They replaced it, of course, but had it been a gift, or I’d been in a hurry, would anyone have noticed? If Amazon can’t keep counterfeits out of their own inventory, what chance do most buyers have?