I came off the Crown last week (week of the 400+ sickies which, I am grateful to report, we were not part of!) and there were hand dispensers located right outside of the "gated" entrance to the Horizon court. We saw many pass them without using them (no wonder why they got sick, DUH!). There is one cruise line, in particular, and if I recall it may be RCL (or HAL) wherein there is a staff member outside the Lido standing there with a plastic bag of Purell which she/he personally squirts into your hands before you gain entry. Perhaps this should be instituted in all ships as at least there is someone there to monitor the situation. I am not saying that there may be a few stragglers who walk right on by, but it seemed to me that this staff member got the majority of eaters.
Is there really a answer to this? People will be people and they're gonna do what they're gonna do, come heck or high water (but preferably, not on a cruise ship).