Something like 99% of all the cars purchased new are spec'd by dealers, not by customers. So the problem really wouldn't be solved by allowing you to select some combination of features for a totally unique vehicle. You're just going to walk onto the lot anyway and pick from what's there.
Or order it from the factory with exactly the spec I want... but 99% of people are too impatient to wait for a vehicle to be delivered from the factory and most dealerships don't give them that option because they want what's on the lot gone.
I get it. It's easier to shift vehicles if they all conform to some common spec because then there's nothing that makes worlds different. You pick this spec or that spec, end of story.
But I've played this game too many times with dealers and I just can't be bothered any more, which is why I drive an 8 year old Volvo that is good enough. Would I like a new car? Of course, I'd love a spanking new truck, but the glory of driving off the lot with a brand new vehicle that's not quite exactly what I wanted just isn't worth the loss of the 30% of value as I leave the lot and certainly not the tediousness of talking to car sales people for a day while they fuck around upstairs trying to stress me out.
I'll bring my laptop and use your WiFi to work. I'm quite comfortable helping myself to your endless tea or water from your service department waiting room while I'm in your showroom. No, I'm not giving you the keys to my vehicle which is parked outside your lot on the street so you can't box me in, and here's a photocopy of my driver's license which is plenty adequate for your needs, the original stays in my wallet. Now fuck off and do your job and if you're not back here with the keys, ownership papers and plates to a new car matching the spec I specified by the time I'm finished this user story, you won't find me still sitting here. You wanna play games, play them with someone else.
I've never had a dealer decline to let me order a car. What they won't do is discount it as heavily as something they already have. A lot of folks don't see the cognitive dissonance in wanting to order exactly what they want (that the dealer knows is their perfect car or close to it) but expecting to get those huge discounts they could get on the oddly optioned puke green car that's been on the lot for 75 days.
LOL how else do you think you'd see these puke green shitboxes kicking around our streets? Nobody actually likes those colours do they? There's a reason it's been sitting on the lot 75 days :P
German cars in the US have option packages, you can only choose from what they offer. Sure, if it's not on the lot you can order it or request an allocation or something, but you cannot specify the precise options you want if they're package-only.
Many Subaru options are dealer-installed so the only option you'll have beyond what comes bundled with your trim package is things like roof racks and fog lights that can be installed by a dealership employee.
Are they imported from Europe ? If so I would understand why you can choose only what they offer.
In Europe (for European brands I mean) you don't have such an issue, as long as you are willing to wait a long time to have it delivered, ( I know people that have waited 9-10 months for their VW only because they wanted a specific color) ).
In the US, regardless of where a car was built, you typically have very few options choices. There's not a significant difference in ability to choose on my made-in-Germany Golf and a made-in-Mexico Golf.
I think, over the years, shoppers in the US have shown time and time again that they simply don't care, so these choices have been taken away from those of us who DO care.
