Went to a camping in the Laurentians in Québec (Ste-Agathe) and there were those things near some camp sites. The sites are only accessible by footpaths. No car access. And if you bring a bike, you have to walk it up a hill, so I doubt they are bike racks.
EDIT: I have sent an email to the park and they have been kind enough to reply. It's just a type of fireplace with a grate. They didn't give more info than just this. Thanks to everyone for pitching in!
That and/or its just been very rarely used as a grill.
If its been months or years between sporadic uses... wind and rain could wash away light, non consistently repeated burn marks.
My guess is some construction team at some point had some extra materials laying around, and either got bored and just fucked around and made this, or got very vague instructions for something approximating a grill, and this was 'good enough'.
Assuming this pic is recent... thats a lot of wear and erosion, and vegetative growth on this thing, I'd spitball guess its 60+ years old, it looks roughly similar to some campgrounds I've been at with firepits that were built in like the 1950s or 60s.