Well...don't knock the plastic corks yet. They're great and I have never had a problem using them...but I digress as that's a conversation for another thread...
Wineries bulk age their wines in barrels the same way we bulk age in carboys. The bung (in their case) and our airlocks serve the same purpose of letting co2 out and keeping oxygen out while the wine naturally degasses. In both cases, the wine isn't bottled until it's aged, oaked (if desired), etc, and still.
Once bottled (in either method) the wine is completely degassed. At corking, it is important to leave the bottles upright for a couple days to let the compressed air escape around the sides of the cork. This is from the pressure created in the bottle headspace by forcing the cork into the neck. After that point the bottles have 'naturalized' the pressure and can be laid on their side to seal the corks and prevent oxygen from entering.
But really, I don't give much thought to degassing my wines. They're almost always completely still when sulfited, and I still give them a quick whip out of habit prior to going into bottles.