Why wouldn't a manufacturer publish a manual? Don't people need to know how to operate them?
It is one fast way to tell a cheesy manufacturer vs a reliable one.
In all the years I have in this business, you would be amazed how many people get a spa with no manual, or if they do get a manual, it is still printed in the previous name the manufacturer was using before their latest corporate bankruptcy.
I would go a step farther, and say if the manufacturer does not at minumum offer manual PDFs for download from their website, expect no service post sale.
But then what should people do, When they really need a manual?