I never have a problem bringing beer, wine or liquor onboard. When embarking, I've noticed that the security is usually (always?) port security, not shipboard security. Although I usually pack my suitcases with beer, and liquor (only cans of beer), and, liquor goes in plastic bottles, I have brought a couple of sixpacks thru the scanners in a backpack on numerous times (these are the bottles of beer).
Returning to the ship from port, booze goes in a water bottle, but, I've also brought a bottle or two of beer back on board as well. It seemed that as long as you're not in their face about it, they have never seemed to hassle me. Granted, I'm an kind looking old soul
I really haven't noticed much of a difference between the various cruise lines, my last cruise was on Princess in Feb.