At the present time we have a mixture of cruisers that booked under Olife, Simply More, or no perks at all. I would think the person that is serving you would need to be able(authorized) to operate the computer system that would either charge you for a drink, know that you have the drink package with Olife, or you have SM. The person filling your water glass doesn't have this authority.
When all this settles out in the next couple of years and everyone onboard has booked under Simply More, then it would make sense to allow basic waiters/waitresses to just Simply pour you some More.
Having said that, much of the problem is space management. I've seen Wine servers, recently, operating multiple corners of the GDR. They were running all over the place, wasting time and effort. If each of them had a section, then they could operate more efficiently. It would seem a real basic concept, so maybe I'm missing something.