For $5 it's simply not worth it. Fee exceeds value. Moreover, if you buy a cup of coffee in a store, you are not afraid that it will disappear. They are afraid that it is just a scam, so they prefer to get something for free because they don't waste anything except time.
So make it $10 or $20. Both still cheap, people are out here buying games for $60+. But the thing that happens when someone spends money on something, generally, they pay more attention to it, do more research on what to do with it, how it works, etc.
I guess I'm saying air dropping bitcoin works but has pros/cons but also promoting buying bitcoin can work, has its pros/cons.