Wedding Costs.

My oldest friend is getting married next year and as we are wont to do we have been discussing it a great deal lately. ( such is the demand for hotels and what not she has practically everything booked) Her wedding is a large affair, and costly, oh so very costly, so costly she laughingly says she lies awake at night staring at the ceiling gibbering softly to herself in terror.
She laughs when she says this, but there is a base note of hysteria in that laugh.
I've got to be honest I too would be gibbering if I was gearing myself up to pay the HUMUNGOUS sum of money she's prepared to spend on just one day. I'd be gibbering and cutting up my credit cards.
How is it possible that a wedding costs so much money in this country? 30, 000 euros is apparently the AVERAGE cost for a wedding, 30 grand! For one day. That's three zero.
Why are we so prepared to put ourselves into so much debt for one day? What should a wedding cost? Why do we put on such a big production anyway? Why spend 5000 euros on flowers? 4000 euros on a photographer? Who is it all for?
I love my friend dearly, however I can't help but get anxious and fretful when she talks wedding plans. Not because I think she's a foolish woman- she isn't- but because on this one issue she seems to have developed a blind spot and I worry she's going to be paying for that one day for years to come.
When it comes to weddings, what do you think the average wedding should cost? And would you be willing to put yourself into debt to get married?