You can buy a Tesla in Texas. You have to order it online and (as the page says) it will be delivered by a 3rd party. You can see plenty of them in Austin. Tesla also maintains two "showrooms", one in Austin and one in Houston where you can see the car, but cannot test drive it or discuss pricing.
Tesla is not allowed to run its own dealerships in Texas, because the auto dealer's union has laws which prevent car manufacturers from running their own dealerships.
Tesla is not allowed to run its own dealerships in Texas, because the auto dealer's union has laws which prevent car manufacturers from running their own dealerships.