Wow....this is the sort of thing that I'd get pissed enough about to take to court. How could they prove empty cans they find on your boat were consumed on the water? Someone must have challenged this already. In a red state that believes in personal freedom no less! I'd expect this from CA! (but the environmentalists in CA would balk at the sid effects!)
Been on the water in KY for decades. I've only ever seen a cooler searched a few times. Typically it's a Conservation Officer looking for people keeping over their limit on fish, not so much for the alcohol side of things. Although I have seen a cooler opened when the CO didn't believe the guy that he wasn't drinking. That didn't go well with a field sobriety test following closely on the cooler check. Keep in mind the CO's in KY have more power than the state troopers. As much as we don't like illegal search and seizure, we protect our wildlife a little more vigorously. Those laws and powers are put in place to address poachers, but travel with the CO to water patrols.
I can say that being on the water here, is, well, odd. As compared to other places I've been on the water (TN, IN, AZ). In those places you don't try to "hide" anything, you just go about your business and don't act stupid. In KY, especially in the lakes closest to the Louisville area (Rough River, Nolin, Taylorsville, Ohio River, Barren, and Green) there is an active "Oh crap it's the cops, hide your beer" mentality. I have never completely understood that to be honest. Every single CO, State Trooper, and Coast Guard officer I've met and talked to has been exceptionally kind, VERY open to conversation, and very open about discussing what is and isn't legal. They have also always shown a VERY prominent lean towards safety over rule following.
On Lake Cumberland for the Poker Run in 2016, we were on a 24ft Axis wake boat in a small cove, after running from a Thunderstorm. 6 adult men on board, and the Coast Guard appears from nowhere. 5/6 of us were significantly drunk. Our DD hadn't touched a drop, and was sitting in the boat with another, while the other 4 of us were floating with drinks in hand. They boarded the boat, searched it for safety equipment, and wrote us a report of what they found. Said to keep the report on hand for future boardings so we didn't have to search everything again, then wished us a safe day and went on about thier business.
I've also watched Louisville Metro Police do great at policing the "bad apples" out of a group of boaters. Anchored in front of Downtown Louisville for 4th of July back in 2008. There was a TINY pontoon that showed up, I mean it was like 16ft long, it was a tiny little thing. 8 or 10 20-something guys on it, and they were having a good time. You could tell there was a LOT of drinking going on though. The police left them alone until after the 3rd attempt at anchoring, in current, amongst 20-ish other boats failed and they bumped thier way through the line of us. As they were pulling in the anchor for another attempt, one guy fell overboard. They quickly fished him out and were having a good laugh when LMPD shows up, takes 3-4 of them off in cuffs, and tells the 1 sober one to "Go home now", and escorted them back to the ramp. The rest of the boats had some obvious drinking, but again, we weren't acting like a bunch of idiots, so they didn't say a word to us, and let us have our evening in peace.
This kind of "common sense" approach to policing of overly tight rules and regulations is what makes the system work IMO. The rules are there, so there is a VERY clear cut line that can be used to determine if you've crossed it or not. We trust the officers to not over enforce, and they trust us to be sensible and safe. That's the more important "unwritten rule" of the water. In the recent years I've been spending more time on IN lakes than KY lakes. On Patoka at least, the CO's are equally as patient and considerate. They'll stop you for out right breaking the law, and if they see something unsafe they'll stop you, ask you to correct it, then let you go with a "be safe out there" before writing a ticket. Watched just this past holiday weekend as they stopped a pontoon boat on the way into the fuel dock. They had a few underage kids without vests on (12+ are allowed without a vest). They made the kids vest up, educated the owner a bit, and sent him on his way.
The drink it and sink it mentality is an old one that still persists. KY has NOT been on the leading edge of environmental protection, ever. One of the worst EPA "supersites" is just south of Louisville in Shepherdsville; toxic waste that will be centuries to clean up. It sucks, but it's where we're at currently. That mentality is decreasing, but it still exists in a number of places. The best we can do it to educate our kids, and others around us, and work as best we can to stop it. I'm unsure if it will ever completely go away, but for the time being I can say it's honestly getting better. I've never done it. My boys will never do it. My grandfather still does it, regardless of what I try to convince him of otherwise. My uncles still do it, but I'm making some inroads there, Usually I can catch them before they let go, and they'll empty it and toss it in the trash instead of the bottom of the waterway.