i would hazard a guess that very few people take their car to a mechanic/workshop and say "could you service and tune my car". they would say "my car needs a XX,XXXkm service" and that's it. very few people would know when the plugs would need changing, or anything about gapping them or checking/adjusting the base timing. if they did then they would ask for that to be done specifically rather than asking for it to be tuned.
and yeah, people would say that their car needs a tune up, rather than a tune, as this is generally said when their car isn't running 100%.