Three meta-examples: imagine all computers were Windows computers, that Windows was the only OS, then everyone would take it for granted and it would just be called "the computer". Whatever biases are built into it -- that becomes "normal". People take it for granted, even if its, I dunno -- (bad example) racist or discriminatory.

Figure vs. ground.

Second example: facebook: its not what people talk about on facebook (not the "messages") but the very architecture of facebook, and the way it shapes conversation. Perhaps this seems obvious and trite to us now, but Marshall McLuhan was writing in an era when it was not obvious - when mass media and television seemed normal, an inevitable part of the background.

Third example: what we call "money" today is really "fractional reserve currency banking", and is just only one kind of money, but has become so utterly dominant, that almost everyone has forgotten that something else is possible. This was not always the case -- in the 19th century, it was very different. The modern conception of money very much shapes the business boom and bust and capitalist cycles, and it need not actually be like that.