I don't recall a single campground that didn't have a cancellation policy. And not all require full payment up front.
I have been to a few that there are no refunds once booked and you had to pay up front, they are mostly private resorts. as for paying up front that seems to be standard for reserved sites up here, the provincial and national sites that are reservation all take your payment at the time fo the booking, but they usaly have a cancelation policy, you never get all your money back as they only refund the camping fee, not the reservation, park or any other fees, and if less than 7 days or you also forfit one night camping fee. no shows are not refundable in any way. or national parks are worse as 8 or nmore days you get everything except the reservation fee, 3 to 7 days you forfit the first night and less than three you dont get anything. mind you I think this is to encourage you to cancel the site early so they can make it available for some one else again.