Some US franchised dealers will order a car for you, but you'll usually pay full MSRP with little room to negotiate. Porsche, for example, does a large fraction of their sales that way.

But custom ordering for many cheaper mainstream brands has become kind of pointless. The manufacturers no longer allow picking and choosing individual options and instead roll everything into a couple of large option packages. So, if you want the good sound system then you have to pay for the sunroof as well even if you don't want it.

Many US consumers expect to buy a vehicle off the lot and drive it away that day. Part of that is cultural. But many customers come in to buy because their old car was just wrecked or broken down, so they can't afford to wait months for a replacement.