They were shocked when they later received a bill from the bride and groom for the cost of their meals. I can certainly sympathize with those newlyweds. I wish I'd had the nerve to send a bill to some of the guests who didn't show up at my wedding. None of them called or wrote to apologize for their rudeness, and, of course, they never sent gifts, either. A bride can spend months trying to make her wedding perfect, from the food to the seating arrangements.
Chances are, the bride and groom are only able to invite a portion of the people they want.
If someone doesn't attend, it not only is disrespectful to the couple and costs them money on food and drink, but also has prevented them from inviting someone else who would have enjoyed the celebration - even in the rain. Weddings are a huge emotional, as well as financial, investment. Lousy weather is no excuse to drop out at the last minute. People who RSVP and say they will attend a wedding, or any other formal affair, should show up. If circumstances prevent them from doing so, they should send a note of apology and a gift to make up for their absence.