For comparison, BMW's models (electric and ICE) offer more paint options, more wheel options, 4x as many interior color/upholstery options, 6 interior trim options, and multiple add-on packages.
Yes, it takes longer, because when you customize your BMW (or any other non-Tesla automaker's cars) you can actually customize it to your preferences, and the customized interior is what can take a few months because BMW (or whichever automaker you went with) is actually building your car based on your customizations, and if you select an uncommon interior/trim/package combination, it can take some time to get to the front of the queue.
You get your Tesla in a week because you're not actually customizing anything. You're just getting whatever Tesla already built.
And if you want a non-customized car and getting it quickly is a priority, you can just go to your nearest car dealership and get a new car in an hour, and whatever that new car is will have better build quality and range then your Tesla. And with Tesla's recent price cuts killing the used Tesla market, your non-Tesla will also have better resale value when it comes time for your next car.
If BMW let me configure a BMW, put down a deposit, and provided me with a delivery estimate, I’d do it. In a heartbeat. But I can’t.
Imagine if Amazon worked this way. You do a search for a new backpack. You get to the page with the backpack you want. You select the size, color, number of pockets, everything. You add it to your cart. Then when you go to pay, Amazon puts up a screen that says “Thanks! Give us your phone number and someone will get back to you. Or, just visit your local BackpackMart and show them the configuration you want.” Hell no! Amazon has perfected the frictionless checkout. Car markers haven’t, because they’re stuck with these worthless middlemen who provide no value to the process whatsoever.
The fact is, I don’t really even want to customize my car down to the stitching. I just do it because the interface on the website makes me do it.