Part of that "other stuff" would be countless hours of finishing/retouching/correcting, etc. Some photographers will spend a week P/T to work through the photos they took on one night.

I think there'd be a few people who get into wedding services expecting it to be lucrative and then find it a lot more difficult than they expect. I've mentioned on here before (check comments history) a client of mine who got married, noticed the huge prices, bought a wedding services business and then sold it within six months - more hassle than it was worth!