it's cheaper to just buy your own pair at that point, not to mention that those skis are usually beat up, and mostly beginner/intermediate level...
This is because they are built to go through the machine after each rental. Good retails skis have less "robust" but faster, thinner base, they would be dead after 3 months of rental.
Source: I spend way too many hours each season in a ski shop taking care of a mix of rental and competitive hardware.
What machine are you referring to here? It sounds like you are referring to some kind of waxing / edge sharpening / cleaning device, which would be extreme luxury compared to the rental shop at my local hill where they intake the rentals for the day and dump them back into a bucket for the next skier.
Maybe for us in the US, this is more equivalent to buying every year and then reselling? Haha.