Well, this is different from reality in the way that law forbids slavery. Also, the norms by which society abides, or claims to function by, are against a practice of the sort.
Moreover, this character’s leashing indicates his position in terms of power relations to the rest.
Subjugated by Pozzo, Lucky’s ‘automatization’ is clearly another factor that makes the play different from reality. It does so by exposing the extension of Lucky’s lack of self determination. His dependence to act on command make him an ‘automat’. Then, when he is left to his own device, as proof of what has been previously stated, he rambles nonsense.
In conclusion, life in in this limbo-like world degenerates character.