To a degree, yes. As was mentioned elsewhere there is a thing called Wave Function Collapse, which occurs when a measurement is taken of a quantum system and forces the system from superposition (multiple states at once) into a single state. A measurement could be seeing it, scanning it, bumping into it, etc (not human conscious observation, that's an old and weird interpretation and not relevant nowadays).
Before (and after as well) you actually collapse the wave function you can perform meaningful math using the quantum particles. The one way I'm familiar with is for computer calculations, which is what quantum computers are aiming for. This is basically done by canceling out certain possibilities to only allow the wave function to collapse into ways that give meaningful mathematic results.
As such, this is barely relatable to a quantum Santa which uses this nature to perform meaningful present sharing actions simultaneously using quantum superposition of a quantum system that is spread out over a very large area. Of course, basic quantum mechanics becomes statistically the same as normal physics (i.e. 10 quadrillion particles average out to one normal human), so Santa would need to be a reality bender to allow for such small chances to occur to allow a human sized being to affect a huge area... but whatever.
Praise be to GURPs! It's unfortunate that there seems to be a persistent sentiment that DMs should be making snap arbitration on a large variety of systems instead of having a rule-base that you can ignore when it gets in the way of your storytelling.
GURPS does this some much better because it does have rules for almost any genre and style you want, letting you have professionally crafted rules that have been playtested and matches to the genre they are designed for that you can use either way.
As someone in the Eastern US (grain of salt there), this rarely occurs but if it does it is usually when a place serves a large group (justified as the extra difficulty for serving so many people at once). If I saw this applied in another situation I would 100% consider that a tip, give them nothing, and never eat there again. If it was applied when I went in a large group I'd say it can go both ways, but I'd definitely not go back there with lots of people again because it feels like its an attempt at fleecing the customer for more than the trouble is actually worth. Alternatively I might tip less, taking the 18% into account already as a tip. Overall, I'd say it's bullshit and a good proportion of the people I know would agree.
Hope your trip goes well