The federal laws in most western countries prohibit the consumption of alcohol not supplied by the licenced carrier. This is also part of the standard international/IATA transport agreement on the use of alchohol in flight, or even on trains crossing state or international boundaries. For domestic airlines, they are not only bound by these federal statutes and international agreements, but also by state or provincial liquor laws. In all cases, consumption of non-carrier supplied alcohol is a breach of license which can result in the loss of the privilege to serve alcohol on flights into/out of the respective jurisdiction(s). This holds for both the United States and Canada, and I expect other countries as well.

It is also the reason you cannot open your duty free alcohol on a flight.

Add to that the whole issue of "air rage" which has often resulted from the clandestine consumption of non-airline supplied alcohol -- particularly in commercial coach cabins -- and I think you will find even those crews who in the past might have adopted the "Don't Ask/Don't Tell" approach, are less sanguine about it today.

Obviously you could always try to smuggle on some Sauvignon Blanc in your Evian bottle, or a Cabernet in a darker plastic screw top Coke bottle, but that's up to you. I have never had my carry-on water bottle opened [to test for petrol or vodka] or confiscated. Now that even the airlines must have their fine wines opened by catering prior to departure -- no corkscrews, screwpulls and the like -- opening a regular bottle of wine in flight will be an interesting act to achieve.