It's eaither the fact that it's hyrule and they want to represent the triforce or it's an awkward coincedence. I think it's the first one and it's in hyrule. I mean check the behind the ruppees artivle about zelda religion. This is exactly the kind of thing they were talking about with the triforce everywhere.
If you look even closer it shows other paterns of the Triforce as well. It's just a design, nothing special. There are Triforce symbols all around Hyrule. They want too keep the legend of Triforce keep going till the end of time. So they just put a bunch of pictures and symbols everywhere too make sure that the people of Hyrule don't forget , but seriously, it's just for looks. As for the Triforce mark on the MM picture...MM doesn't refrence the Triforce in the game...at all. Most likely because it does not exsist there.