In my first restaurant job as a cook during college, I worked in a steakhouse using a manually written ticket system. The servers carried their own "bank." The tickets and cash or credit card receipts were turned in to the manager/owner at the end of the shift. She then manually entered each server's drop on a sheet (sometimes in pencil).
What could possibly go wrong?
Although technology can significantly reduce errors in manual processes and increase efficiencies, restaurants have historically been slow adaptors. The move to POS was a perfect example.
Why? Because nobody wanted it.
With a POS system, the servers couldn't steal as much and the owners couldn't skim as much. Everybody could still do some "grocery shopping" in the restaurant's walk-in but even that would be reduced with improved inventory controls. For many private owners, it became a cost-benefit analysis. Do the better controls outweigh the reduced skim?
In the end, tech won out as it almost always does. Today, we have extraordinary tools to help us manage our restaurants. Nobody is willing to go back to time cards, give up our theoretical food costs, or forget about geo-targeting and our seamless interfaces (when they work). A restaurant company in this world has endless discussions about the tech stack and worries incessantly about whether the credit card processor is the real controller of their loyalty program.