Your local restaurant or cinema doesn’t have diversion costs, FTL concerns and compensation for passengers. And hopefully an ambulance can arrive quicker than to an aircraft at 40000ft. Severe allergy reactors can also “easily” avoid those places, but if one need to travel it’s hard to avoid flying. But yes I do agree it’s almost a pointless gesture, but if the PA lowers the risk by 1%, then it’s going to be made. For the airlines benefit as much as anybody else’s!