Yes, and if they do, there is a risk of company exploiting that person and their co-workers for underpaid labor. One worker’s enjoyment of work does not justify this risk.

Who said they were underpaid?

Nobody, but you must see how this can be abused to do so. A system that can be abused will be abused given the right incentives. As it stands companies are incentivized to pay as little for labor as they can get away with, and if they are allowed to “allow” workers to work excessive overtime, they will. And it will cost every other worker our free time.

If you enjoy your work, that’s great, just do your work during work hours, don’t use your free time to undervalue other workers in the industry.

I'm simply saying you don't know the situation, how GP was compensated, etc.

Yes, shit companies exist and abuse their employees. You quit and move on. There's no indication that this was happening.

I think we might be arguing about different things here. You’re saying that it worked for OP, that is fine, I don’t disagree with that, however I do disagree with this practice, because as a whole it is not good for us workers in this industry. This behavior is ripe for abuse, and companies do abuse it unless there is a collective action against it (through regulation, union contracts, etc.)

Like you said, if you work for a company which expects this from you, and you quit as a result, they can simply hire someone else that takes the abuse, and that is not a good prospects for us workers in this industry. Which is the reason I’m asking OP not to do this. Even though they had fun and were handsomely compensated, this behavior does a net disservice for the rest of us.