When I was growing up, there were elevator operators in all the high-rise office buildings in Downtown Pittsburgh. When you drove into a "gas" station, someone came out and cleaned your windshield, checked your oil and tire pressure, and collected the money, all without charge and certainly with no expectation of getting a tip. When you went into a retail store, there was a clerk on duty who helped you find and select your purchase.
Crappy jobs all, and all gone now.
When the cost of any commodity goes up (human effort being a commodity), the users of that commodity look for ways to use less of it, or stop using it altogether.
Human nature.
If a $15/hr minimum wage is good, then why be niggardly about it? Why not $25? $50?
You can't buy a house on $15/hr, or put a kid through college.
Tell that to a person working a MW job and see what they say. Paying $15 per hour could make a big difference in their lives, but you don’t care about your fellow Americans. Fuck them. Right?
When I was a teen working as a Pump Man for Exxon, sure I would have loved to have the corporation pay me $15 / hour instead of the $1.60 they were ponying up. It would have made a big difference in my life as a teen.
But it just wasn't viable for XOM.
Those same Gas Stations went self serve when min wage was $2.00 an hour
They do it because the technology is there
And because someone in a back office ran the numbers and convinced the executives that the self serve pumps would pay for themselves within a reasonable amount of time. They would not have automated if the self serve pumps were more expensive.
Actually, the self-service gas pump kind of worked like this. A local gas station fired their pump guy, you know, the one that came out, pumped the gas, washed your windshield and checked your wipers, and then took your money while you sat in the car. Then people had to get out of the car and go inside and pay. But now the owner of this particular gas station could charge a little bit less for his gas. All the other gas stations in town still did it the old fashioned way. But, since everyone is so damn cheap that a couple of cents on the gallon of gas was going to save them so much money, well hell, they didn't even mind getting out of the car. Soon, all those other gas stations fired their pump guy too.
Now, to the self-checkout at Walmart. People don't mind the self-checkout because lots of them, well don't "check-out" everything. Walmart might save a little money on labor, and they are so damn averse from paying labor. But, their shrink goes through the roof in some locations, and it goes up in every location. The OP claimed the "host" was watching 20 registers. I doubt that, six is about the max. But if she was, I can guarantee more merchandise walked out the door than any savings that store was getting from a decline in labor cost.