However, how many do you think they might sell, after spending many thousands of dollars, doing research, editing, and publishing?
I would guess probably one copy.
That first purchaser would offer free copies to everyone who might share the same interest.
We started a manual about Airstream service, upgrades and modifications, based on my 37 years experience with the product.
We quit it simply because of the costs involved, including tons of time, and the fact that distribution of free copies, by others, is almost a guarantee.
Sure, you can sue them, but, we are in the service and parts business, and don't have the time for lawsuits.
Not a good incentive for making a substancial investment in time and money.