I'm sure SE uses the actual definition of housing, just as most of the rest of us do. Here, I looked it up for you:

hous·ing1
/ˈhouziNG/

noun
1.
houses and apartments considered collectively.
"a housing development"
There's no presumption going on.

I absolutely agree that SE has not only poorly designed the system but also poorly promotes it so it lends the impression that players are supposed to be able to get a house and not just an apartment. That's no doubt due to apartments not even being added to the game until patch 3.4 so originally a house was the only option.

But it's also normal for advertising to highlight the best of a feature instead of the more common elements. If you're watching a trailer for a movie, you're going to see the action packed clips instead of the clips where characters are just talking to each other. If you're seeing an ad a cable or satellite service, they're going to be showing clips of sports and popular movies, not clips of the local evening news or a nature documentary.
Anyone who eats fast food knows that what you see in their ads is not how your food is going to look when you get it.

And so SE uses a picture of a house for their housing advertising instead of an apartment. It's the standard way of doing advertising.

It's promotion that's the problem. Advertising is only one part of promoting products. If SE isn't going to change the system from what it is, then they need to up their promotion game to make the realities of the system apparent to players.