It is not legal in the US to pay employees using scrip:

https://www.law.cornell.edu/cfr/text/29/531.34

> "Scrip, tokens, credit cards, “dope checks,” coupons, and similar devices are not proper mediums of payment under the Act. They are neither cash nor “other facilities” within the meaning of section 3(m). However, the use of such devices for the purpose of conveniently and accurately measuring wages earned or facilities furnished during a single pay period {{ is not prohibited. }} Piecework earnings, for example, may be calculated by issuing tokens (representing a fixed amount of work performed) to the employee, which are redeemed at the end of the pay period for cash. The tokens do not discharge the obligation of the employer to pay wages, but they may enable him to determine the amount of cash which is due to the employee. Similarly, board, lodging, or other facilities may be furnished during the pay period in exchange for scrip or coupons issued prior to the end of the pay period."

Gig economy my friend. Back the currency in some nominal amount of USD and pay the independent contractor at the door 1 walbuck per customer greeted.

So long as the employer provides a free token-USD exchange that pays out to employees the cash amount equal to their wage I don't see an issue; people can do what they want with their earnings.