I was only talking about the tax in Quebec, and as you stated, it is much higher indeed. However if you consider all other costs, i.e. property tax, child daycare cost, tuition, etc., it may be worthwhile to move to Quebec, but the situation is different for each family, there is no set "rules". Then you'll need to learn to deal with the language, many people find that difficult.
When I lived in Montreal, water was part of hydro bill, but it wasn't free.