Voice control cash registers.

And move the cash from the customer into the register?

There is an image from Munch Oddysee that shows the differences on wich class. Dunno where it is.

EDIT: Here it is.

So, by this image, here it goes:

Molluck: Big Cheese
Brewmaster: Wanna-be/Chump
Dripik: Big Cheese/Wanna-be
Aslik: Wanna-be
Phleg: Wanna-be
Lulu: Every class

Play MO again. Note how money transfers are performed. Physical cash is not involved.

You know, something about two-dimensional quantum-locked decals of the wrong currency symbol materialising out of a Glukkon's person and tumbling dramatically into baffling anti-vending machines always struck me as a necessary game mechanic rather than an actual in-universe rendition of the Oddworldian financial transaction process.

I just figured they used credit cards. Or some Oddworld equivalent that doesn't need hands.

or the machines had mechanical arms