Originally Posted by clemmb
The camera that this person is looking to buy is a first DSLR. You had two DSLRs for your wedding work. If this person is doing wedding work for a fee and their one and only DSLR should fail, they will have no spare DSLR unless they have rented a spare. That was my whole point, as evidenced by the "safe" reference and the movie quote which referred to redundancy in another setting.
Hopefully you'll notice that none of my comment relates to expensive high tech gear, and none of my comment relates to skill and/or practice. Expensive gear can fail (my 1D Mark III did, 16 shots after a trip to Canon, and it needed a new mirror box), and there's no amount of photography skill or practice that can fix a failed or broken camera.
You're right about knowing your tools, at least with regard to knowing that your tools can fail.
I shot a wedding once, for free, with a single camera. I knew that I had a battery "issue", which turned out to be yucky off-brand batteries, but the camera did freeze on me once. I shouldn't have done the gig with one camera, period.