It's not that they're blissfully unaware. It's being thaught in school and almost all official writing is done in the so called 'written German'. But it's simply not the language you speak (safe for a reason to the contrary, like not everybody understanding it). Even in written (private) communication it's used quite a lot, like in mails, sms, ...
Oh, and at least for Swiss German: It is kinda a different language (but extremely related to the written German): It's not just an accent with some funny words, but has a slightly different grammar, too. Most glarious is the lack of most of the verb tenses in Swiss German. So pupils have to learn quite some stuff to be really fluent in written German.
And even just within Switzerland there are dialects I don't understand (as in no clue what they're talking about). People speaking these usually switch to a more conformistic pronounciation when talking to people from other areas and don't use some of the more obscure words.
And for the reasons this all exists (at least for Switzerland): It's cultivated and all kinda part of your local/national identity. Politicians who speak a "too good" written German are deemed suspicious, almost all of the local culture (theater, local movies, even most of the Swiss tv produciton ...) is in Swiss German.
In DE, ~everything~ on TV is in 'high level' German. Bah, we even dub every movie, special we-show-you-the-real-thing cinemas notwithstanding. Still, you have local dialects that are mostly used on the streets. Often these are part of the local identity, part of belonging to a place and people speaking different (even if that means 'correct') are easily identified as outsiders. I guess it's just a natural thing: I regularly hear people from the USA joke about southern/northern/eastern/western dialects as well - and Europe had a couple of years more to develop those.
Switzerland is a very specific case, I guess. The level of national pride is very high, with a very prominent political party living close to the racism edge (and crossing it every now and then), protecting the country from outside influences (contractors from i.e. Germany are not really welcome there, often seen as stealing jobs).
Add to this national pride a good amount of _local_ awareness: CH is a federal system, each 'state'(Kanton) fighting for as much independence as possible. Heck, they don't even have a real capital city [1] because they don't want one state to surpass the others. Your local region of origin seems to be much more important there.
In addition CH has 4 (erm.. 3.5?) official languages and already some 'borders' that separate parts of the country into ~mostly french/german/italian regions. You drive 5 min and every sign switches from German to French and the whole culture changes (food, lifestyle are the easiest things to spot).
I mean, why would people be blissfully unaware of the standard form.