Well, since you asked, my answer is the people who hire my band to do an important job for their venue or event definitely care. They care about snafu's, a lot, because when the band tanks or has issues, it is a poor reflection on them as well, and I'm talking everyone from the corner bar manager to the wedding or corporate event planner.
lol. In my world, it is possible to book what we call a "big gig,"( i.e. very important to the client (and his patrons or guests) who is paying us a decent wage) and still have to schlep your own gear. This is the norm in my neighborhood.
That explains a lot. I told you, we play in very different worlds, but I'm not a touring superstar by any means. Just a weekend warrior in a kick-ass party dance cover band. Not to boast, but our performances are definitely a step above "paid rehearsal."
No "stars in the eyes" syndrome here friend. Just serious weekend musician-entertainers who take pride in their work and do what they can to not get tripped up by preventable situations. That's all.
And what our gigs are is, they are important enough for us to bring spares and backups to the extent reasonable and responsible to ensure success for the individual musician, the band, and the client. We call it the WIN-WIN-WIN.