OP, when you sell someone a bike, do you talk to them about the maintenance regime required? Do you tell them what they need to lube, what they may need to adjust, which parts will wear and need replacing, when to bring it back to have a proper mechanic look at it? Because if you don't, how are they supposed to know?
Generally, the free first service is the ideal point to go through that, I find, rather than bamboozling people who are more focussed on getting a new shiny thing. You get a feel then for if the bike is used occasionally or daily, in all weathers or on dry sunny days, kept indoors, garaged or tied with a piece of string to the drainpipe, and can advise accordingly.
Lube is generally suggested along with the other accessories but when people are adding up cost of lights, lock (bizarrely the lock is when they start to skimp, after spending on the other things that will get stolen without a decent lock), there tends to be a "stop trying to sell me more things" line.
But..come to think of it, I wonder if producing a little maintenance leaflet and giving a "free maintenance kit" with a little brush and some lube might not be a bad idea...
Although I get the feeling in this case, that it would have gone in the bin. I'm not bothered, I'm not the one who still has a squeaky wobbly bike..