The situation with BitCoin is that it is not recognized by the feds as a currency. It is considered an investment. So, companies that accept and use BitCoin have to do double the accounting.
First, they have to determine the fair market value in the local currency (assume US$). So, if today a BitCoin is equivalent to $500 US$, then a company will take 200 BitCoin to sell the car.
Later, the company uses 150 BitCoin to purchase materials from a supplier where the price of the BitCoin has risen to $600 US$. So, the Company has a transaction to show an expense of ($600)(150), or $90,000.
Then, there is an investment gain of $100/Bitcoin, or $15,000 that must be recognized as revenue.
Since the price of BitCoin fluctuates, the accounting for these occasional transactions would be more trouble than it is worth. Factor in the fact that Tesla would collect sales tax in BitCoin, but remit the tax to the states in dollars, and suddenly Tesla is out-of-pocket.
At this stage in the game, Tesla does not have the need to accept alternative payments for their products. Cash flow is everything to Tesla, and for Tesla essentially to take payment in kind or through bartering, is going to put a crimp in their cash forecasting models.