Would You Like Wine in Your Doggy-Bag?

Texas allows you to transport open but covered bottles of wine in your car. Even when there are only two of us at dinner, rather than buying a glass of wine for each, we buy the whole bottle and take home what’s left.
Everybody wins: the law that allows transporting the wine creates a Pareto improvement. The restaurant is better off because it sells a whole bottle at a substantial mark-up. With three people, the cost to us is almost the same, and we get the leftover wine; and even with two people, we get access to good wines I might not see elsewhere.
Finally, this creates a positive externality; after buying a bottle in the restaurant, I don’t feel compelled to drink more than would be desirable and possibly create a hazard while driving home. Recognizing this, more states are allowing transport of open bottles, although in some (Illinois, e.g.) the restaurant must seal the bottle in a special bag.
(Hat tip: D.B.)