Having worked at a music store (not guitar center) you’d do that all day long if you tried. I swear, the first thing everyone does when they pick up a guitar, is start fucking with the tuning pegs (whether it’s already in tune or not).
A lot of times our sales guys would tune it real quick, while they talked about the guitar, before they handed it to potential customer.
If you believe the web site, my nearest guitar center currently has 543 guitars in stock, some of which can only even be reached with a ladder. So if you assume one minute each to take them down, check the tuning, put them back, move the ladder, etc., you're at about 9 hours. A fair bit of that time will be spent just to see that it's already in tune anyway.
And Guitar Center in particular is in the phase of its life where private equity is pulling every dime out of the business until they can eventually just shut it down and sell the real estate, so they're not paying anyone to go tune guitars. You're lucky if they're paying someone to clean the bathroom.
Mine probably had three rows of 50. I’m guessing only the bottom row would need major tuning daily. Even the Floyd Roses were so out of tune they were unplayable.
It will be a shame to lose more brick and mortar stores for an item that you really need to try before you buy.
The setup will vary from player to player, but a basic standard setup should be done before it even goes on display. I just assume that the high action is covering up uneven frets.
It would be interesting to see a blind test of preference on a group of random guitars off the wall, and then again after a setup. The playable ones may just be setup better, rather than better instruments.
In Japan all of the guitars in shops (no GC here) are tuned by a clerk when you are ready to play them. I'm pretty sure the strings are also slackened when they go back on the rack.
When I bought my guitar, I bought 3 extra packs of string and an electronic tuner tool. Tuning the instrument was the first thing I learned how to do with it. Seemed rather important to know, you know?