This is a common misconception. There are much stronger ties to ethnicity and gender, and the age assumption is just wrong. in the US, 2/3 of those making minumum wage or lower (tipped jobs) are women of any age. The majority are age 25 or older. These incorrect stereotypes mislead people into mischaracterizing who is getting paid minimum- wage and making the same assumptions that this is labor done by the unskilled and those who are young and don't need to support a family. That is dreadfully incorrect.
Source:
Characteristics of minimum wage workers, 2020 : BLS Reports: U.S. Bureau of Labor Statistics
Plus creating additional jobs in the creation and servicing of the kiosks - a net win as we still have people employed but in more productive jobs. But to be serious, many jobs require physical, social or service aspect a kiosk can not provide. A supermarket may have a few self-checkout lanes, but can't have only self-checkout lanes.
Walmart will make some new higher paying jobs either directly or indirectly, and will employ less low paying workers. Historically we've moved down to 40 hours weeks from much, much higher. Well over 80 a week for agriculture (the primary job) back when the US was founded, down to 68-74 as an average during the Industrial Revolution in the early 1800s. In other countries besides the US it is already lower than 40, and in many of the European ones you are starting with 4-5 weeks vacation and the like. Automation will
and should reduce the total hours of work done overall.
Source:
History of the American Workweek | Timesizing®
There's been studies of these in the various places that have upped the local minimum wage, and we aren't seeing this. But then again, it is a myth that they are the majority of minimum or lower paying jobs in the first place.
Don't forget lots of great trade jobs. No college required, but skilled work that pays well. Plumber, electricians, etc.
There is not a human cost in moving from 40 hours of low paying to say 35 hours of mid paying. Automation is making everyone more efficient. Reducing the total hours needed has been a historic tread for centuries, and is playing out well in other countries.
But this brings back the myth that less work means less pay, when less but more productive work can mean the same or more pay. There may be an adjustment period where there is unrest - there often is during times of large change - but it will work itself out.