A couple of weeks ago (or more, or less; my sense of time is hugely distorted) I had an interesting semi-discussion via comments withon the subject of etiquette.
I personally hold the belief that the concept of etiquette is ever so ridiculous: a set of old-fashioned rules which people must adhere to in order to appear 'respectful'. In my opinion, people in general put the ideas of etiquette and respect together, whilst I see them as very different things. Take the example of what to wear to a wedding. According to the unspoken (although often written) rules of etiquette, black is the suitable colour to wear. Modesty should be preserved.
To me, this 'rule' is hugely ridiculous; that something like the colour and cut of one's clothing can be a sign of grief/respect/whatever seems to undermine the importance of the occasion. However and this is important, I understand that some people enjoy and place a great deal of importance in tradition. It is out of respect to them and not the laws of etiquette, that I would wear black to their funeral and not to their weddings.
But with the issue of thank-you cards I simply cannot bring myself to do what is deemed polite. I have never before sent a shop-bought thank-you card because I believe in the power of a kind 'thank-you'. I have mentioned on here before that I put a lot of effort intomy home-made cards and as a result, I am not willing to send a thank-you card to every single teacher at the end of the school year, nor every single person who gives me a birthday gift. When I do say thank-you, it's not etiquette but gratitude.