I assume GP is assuming it would be hanging freely in (in-wall) conduit, which is pretty uncontroversially the best way to do it, just very hard to retrofit.
And if you are retrofitting a cable run, yeah it probably will be 'just hanging freely behind the walls'.
I've been in a newly constructed home with Cat-6, and they stapled it. This was within the last year.
From builder's perspective it is "controversial" to run conduit because they're trying to tick boxes as cheaply/fast as possible and conduit is the exact opposite of that goal. If you want conduit, I'd assume you have to pay for it as a bespoke upgrade.
And if you are retrofitting a cable run, yeah it probably will be 'just hanging freely behind the walls'.