Let’s take that one step further. The 18 year old has a high degree of manual dexterity, and is noticeably faster than the 35 year old, and is more accurate (facing is an issue; shelves have little or no “spare space”).
The 35 year old is slower than average (meaning, noticeably slower than the 18 year old, and measurably older than other shelf stockers).
Now, where do we go? My recollection is that Walmart is not unionized (out here it would be Local 1053, if I recall from 50 years ago when I worked part time in grocery in college). Because the unions are divided into locals, the rates vary and are driven at least in part by local economies. In some instances, starting pay is between $8.40 and 9.50 an hour. an average top-out is about $17.hour, again with variations based on local economies.
Additionally, grocery stores on average have a profit margin of about 3%. In other words, they make money on volume; lacking volume, they will fail. Walmart has exercised two options: they provide mediocre products (e.g. clothing) and price food products at or slightly below local competition and has gone to the store model of “one stop shopping” to drive more business. I don’t know their profit level, but I doubt it varies significantly from the norm.
And if we decide (as a number of jurisdictions have) that we will have a minimum wage of$15/hour, in other words almost what a 5 year journeyman at peak would earn, we are either going to have tremendous wage compression, or we are going to see acceleration of the wage scale.
Accelerate the wage scale, and the store is faces with one of two options; raise prices or reduce work staff.
In short, it does not matter what the background (age, children, home/apartment and any other details) of the employee is. What matters ultimately is what is the cost of having the door open to do business with customers in the morning.
I am well aware of pay disparity between owners of companies (particularly large ones) and the “worker bees”. But it is also a fact that productivity has a direct effect on the bottom line of a business, large or small. Paying based on age and family issues (kids, mortgage etc.) is totally irrelevant to production.
Retailers are going out of business or bankrupt in spite of paying retail clerks minimum wage, as Amazon is eating their lunch. You can demand the local bookstore pay its clerks a minimum of $15/hour (Seattle has done this) and it will simply result in the bookstore closing - which does the worker how much good? The same goes for the chain bookstores; one by one they are going, going, gone.
So now, blackforest, how do you wish to roll it?
I understand thoroughly the issues being asked. I also understand that many who promote higher wages have a) never rund a business of any sort having employees, and b) have a whole lot of false assumptions as to what may or may not be possible in wage structures.