I doubt the pilot will admit to knowing when under oath. I think it would be impossible to prove the pilot knew the passenger was over the limit for driving if they said "I had no way of knowing without a breath test meter if the person was intoxicated". How many people are drunk from the airport bar when they get onboard? Are the pilots remiss for not checking each one as they board? Are they held responsible when the guy causes the aircraft to be diverted for bad behaviour. I know what the regs say but has anyone ever been violated for that? Imagine the corporate pilots who would be between a rock and a hard place if they really had to check their VIPs. Uber better look out with their taxicab helicopter ops. The rules are fine but there are many that are difficult to enforce.