That's difficult for people with poor science educations to fully grasp. For example, they might think that the moon's surface itself could reflect the laser light, etc...
Not to mention that unmanned probes could also have placed reflectors without humans ever being sent to the Moon!
Scientists have reflected lasers just off the surface, and there are unmanned probes (Russian ones) that placed reflectors on the moon.
But the point should still be that, if anyone cares to learn about the difference, and how we know the difference between all these different types of reflectors, that information is freely available and could easily be understood by most people.
Why even go to those lengths? If they lied about the moon landing surely they are lying about lasers even hitting the moon, or it not being made of cheese...
Not to mention that unmanned probes could also have placed reflectors without humans ever being sent to the Moon!