I disagree --- because I haven't seen it --- they don't want to make the investment that it takes to retain and train good employees. It's like expecting friendly service at the K-Mart blue-light special line --- if you're looking for cheap you get cheap.
When I see that long Walmart return line snaking through the store, I wonder how I could stay a friendly helpful clerk. 'Oh sir? You want to return this $4 Chinese made toaster that lasted you 3 times? You're upset? What did you expect it would last?' or 'You paid $9 for a blender for the 5th time and you're angry that you have to return it again? And you're upset that you stood in line for 45 minutes behind all those many others?'
Sure but, what we're missing to test our theories is
high unemployment. If the willing-to-work-for-the-government-imposed-minimum-wage labor pool is large enough, I expect competition among the retailers (for customers) as well as among the laborers (for jobs) has a way of working things out quite nicely, without any need for your employers to "invest" in their employees.
It's just simple economics.
Someone has said "What this country really needs is a good depression." Perhaps there's a hint of truth to that.