Possibly, but that doesn't explain why (as J187 notes) they so often tile the floor before the walls. That has always puzzled me, too.I suspect the reason they tile first has to do with their deadlines. They only have so much time to film the show and complete the project so anything that takes substantial drying time (like thinset and grout) gets started first.
And gma2rjc's right, I've never once seen waterproofing of shower walls discussed, except once when they put plastic behind the backerboard.
I'm only partway through my first bathroom (my own), so am basically an ignoramus about this, but I'm curious: Why would you paint after tiling? Seems to me if you do it the other way around, there's no need to worry about protecting your nice new tile floor from the occasional paint drip or scuff damage from the ladder/staging/etc. For this reason, I was planning to 1) put backerboard on walls, 2) paint drywall, 3) tile walls, 4) put backerboard on floor, 5) tile floor. I realize it's not maximally efficient but is there any other reason not to do it this way? Thanks.