Even at private parks where they advertise wifi, we have found that means there is a hot spot at the office, where you have to sit out on a picnic table swatting black flies or mosquitoes. Since crossing back into Canada, most parks have been that way. I do know that those framily who have come east the past few years mostly had satellite, and a few had 3/4 G wireless. We've never gotten wireless as the price for a Canadian supplier is outrageous, and with only 6 month maximum stay allowed in the US, a US plan becomes expensive too.
As for Provincial Parks, stay away from Ontario as they are way over priced for what you get, there are usually nearby private ones with full hook up for less than you pay for electric only. We have been able to use Passport America, and plan on doing so again when we leave our daughter's for home tomorrow.
Ed