I was actually thinking of horror stories I have read about photographers who don't show up for one reason or another, memory cards that fail, cameras that are stolen, film canisters lost, and so on.
The laws are different in the US than they are in the UK. In the UK, wedding photographers failing to do their jobs have been legally forced to fly the wedding guests back in, pay for the entire event to be restaged, everything, just so it can be shot correctly. Not so in the USA.
For horror stories, use Google News and search for 'wedding photographer sued' or 'wedding photographer arrested' or 'wedding photographer' and 'fraud'. You'd be amazed.
And one last thing - shooting weddings for friends strains the bonds of friendship. If the relationship is not strong, it may not survive.
If I shoot for a family member or friend, we have to agree ahead of time that they are engaging me NOT because I am the family photographer, but because they don't have another choice (perhaps due to budget). They are getting my best effort, but I am not a professional photographer and they get what they get. If they look over the album later and feel shortchanged, they got what they paid for. If they think they're doing me a favor by engaging me, or that hiring me is a family obligation, it's not. They should hire a wedding photographer if they can; I will not object, hold a grudge, or complain. I'd rather be there as a guest anyway. Do not hire me because we are buddies. Bad idea. If I were studying dentistry in my spare time, would you have me do your root canal?