This is such a dumb, simulationist complaint. Even if we accept the premise that halfling culture as-written is averse to adventuring (which for the record I don’t), it doesn’t follow that that makes them poorly integrated into the setting or “written like NPCs”
Don't forget that we also have made up stuff like elves are all mighty warriors because elves that become adventurers are assumed to be representative of the majority of the population.
If you try to hold up most aspects of D&D worlds (especially ones like FR) to a simulation of "reality" they tend to fall apart depending on your assumptions.