Not being a hi fi dealer but a wholesaler to them, I can tell you that every single time I loan pair of speakers to anyone, no matter how skilled, the speakers come back with some form of damage. Especially if they are shipped. Enough damage that I can no longer sell them as new and must discount them by 10% to account for damage. The cost is real for the dealer and he cannot pass this cost on.
No one blames the user, we all know this happens, but nonetheless you can't loan all your new speakers out for trial as your entire inventory is damaged. Some dealers do this by having a dedicated loaner inventory. Or are good about having enough sales that they can sell off the "B Stock" as they go, and keep shipping new stock. But it's worth considering that demoing a 50,000 pair of speakers in your room will cost someone 5,000. This is why not everyone does it.
Brad