From what I understand, it's pervasive in America, like if you buy a house you're likely to be stuck with one? A lot of American posts on reddit are like"So I wanted my kids to be legally allowed to go to the only good school in this town, so due to school district boundaries that means I literally could only choose between these five houses, all of which had HOAs... "
In Canada they exist but they have different levels of severity.
If you live in a "apartment condo" (a flat, but specifically the kind you own, not the kind you rent): Usually these have strict rules, but also you live in a flat so it's not like you have any room to put up illegal Antique frog statues or whatever. So people aren't usually very personally inconvenienced by the strict rules.
Example: I used to live in an apartment condo in vancouver, and we weren't allowed to dry our laundry on the balcony?! Scandalous... But Not a huge issue since vancouver is so rainy it would be pointless anyway. We also weren't allowed to push snow off the balcony so we had to spend ridiculous amounts of time piling it into buckets and melting the buckets in the bathtub?! But again, not a huge issue since it snows about 0.75 times per year in vancouver. We also weren't allowed to smoke weed (which is legal in Canada) on the property?! But our neighbors all did anyway so it wasn't enforced at all, so not a huge issue.
If you live in a "townhouse condo" aka a terrace house, though usually in Canada they aren't arranged in terraces, they're arranged in ugly little squares around a rundown parking lot because Canadian architects hate all things that bring joy and beauty to the world:
These are basically like living in an apartment condo but you get a tiny yard("garden" I guess brits would say). Usually if you live in one of these, everyone in the terrace pays $100-500/month in "maintenance fees" and these go into a shared fund for all exterior maintenance eg. Lawn care in common areas, Snow removal, roof replacement, repaving the depressing hell scape of a parking lot once every 20 years after the potholes get so big that someone could lose a golden retriever in one.
Here is an example of what these places look like (feel free to walk the Google maps pin around the area, I picked a location between three complexes)
3890 78 St NW https://maps.app.goo.gl/oxZYuDKWTDNoUN598
Example: I see a lot of posts on /r/cozyplaces like "look at this addition I built onto my terrace house in London!" LOL. You can't build additions onto a townhouse condo in Canada, what a joke! You can't even paint the outside of the house to be a different colour than your neighbour's. You can do anything you want with the inside, but you can't touch the outside. Because like I said, it's basically like living in a flat, but not vertical. (exception: it might be different in the old parts of Canada that look like Europe. I vaguely remember Montreal having more European style urban planning laws.)
Special mention: There are a LOT of seniors-only townhouse condos in Canada. As in, you literally aren't allowed to live in them unless you're over 50 (or 40, or 60, it varies). They're usually in places that are great for seniors, like right between a doctors office and a grocery store, and they're usually like 40% cheaper than similar non-senior-exclusive homes.
(If I was a good person I'd be happy that seniors have such lovely places to live, however I can't drive for medical reasons and that is a fucking shitty status to have in North America as you probably know, so I'm really angry and bitter about it. all the affordable homes that are actually convenient for non-drivers are for seniors only! Holy shit, I just want to live somewhere where I don't have to walk 15 minutes in -40 Celsius on an ice-covered sidewalk to catch a train! Get your shit together Canada, you asininely designed country!)
If you live in an actual house with an HOA:
Canada doesn't have the America style HOAs, which are insane. I've heard stories online like "my hoa says we aren't allowed to park certain types of cars in front of your house but you also aren't allowed to build garages so I'm not allowed to park near my home" WTF?! no, we don't have that.
However, we do have neighborhoods with "architectural guidelines" where you aren't allowed to paint your house any colour other than beige, and I believe you have to pick between only about five different Floorplans, based on how similar the houses look. Here is an example of what those neighbourhoods look like.
Coventry Gardens NE https://maps.app.goo.gl/XixW2yZ8iHjhAWcw5
Most Canadians seem to despise these areas, and rant about how they look like "creepy bland cookie cutter nightmares, seriously look how everything is beige, it's literally hell on earth", but honestly I don't mind them, maybe because I grew up living in terrace houses which also tend to be beige and identical? I mean, look at the terrace house example, it's way more beige and hideous. I used to live in one of the Floorplans in that terrace house example, too, actually! I'm showing you the real working class Canadian lifestyle, here.
Anyway, these neighborhoods don't really have strict rules other than "all houses must look identical". You could still make your yard look weird if you wanted. Personally from ages 16-18, I used to live in one almost identical to the one in the example I included (you can see the Floorplan I lived in actually) , with my very "white trash" family (Canadian version of chavs?).
And we filled our front yard with broken down appliances, and filled our back yard with broken garbage bags and piles of broken bike parts, and nobody said a word. We even refused (due to poverty) to repair our dangerous illegal front sidewalk and nobody ever reported it, which was surprisingly kind of our neighbours. Definitely not the way you'd expect people in an "HOA neighborhood" to behave!