It was either on this forum or the pool and spa forum where this came up. PST does not get charged if the dealer installs the hot tub. I think they just roll it into the cost of the hot tub but the dealer is responsible for paying it.
I think that was the reason our dealer gave.
So on a side note, if a dealer in Ontario is charging you the PST they are only pocketing the difference between thier cost and the retail price.
Pathfinder or FamilyBiz may be able to help clarify this, thier both Ontario dealers