Job site Glassdoor has just released its list of the top 10 big employers for high school graduates. More than half the companies that earned strong reviews from workers without a college degree are retailers, including list-topper Costco Wholesale (NASDAQ:COST) and department-store chain Nordstrom, (NYSE:JWN). All but one are publicly traded companies.

While the debate about raising the federal minimum wage goes on, and fast-food worker strikes make news, it's worth examining what sets these companies -- many of which offer low pay, at least to start -- apart from companies whose workers are walking out.

Shrinking opportunities for high school diploma holders

There's been quite a bit of media discussion lately about the value of a college degree, but the fact is that earning a good living without one usually isn't easy. High school graduates who aren't enrolled in college are in a job-market bind these days. The relative value of a high school diploma has decreased, college tuition costs have risen faster than the rate of inflation during the past several years, and jobs that don't require a college degree are increasingly difficult to find.

According to the most recent Bureau of Labor Statistics report on the college and work activity of recent high school graduates, 31% of those who didn't move on to college are unemployed -- a dramatically higher number than the current 6.2% overall unemployment rate.

High school grads who do find work are likely to discover that it doesn't pay very well. The federal minimum wage is $7.25 per hour, an amount that most of us would be hard-pressed to survive on for any length of time, let alone also save for further education. That's why it's important that workers without a college degree seek out employers who give them a chance to move up, earn more, and get training for career advancement -- things that workers say they've found at the companies on Glassdoor's list, ranked on a scale of one to five.

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Livable pay and quality benefits

Costco, at No. 1 on the list, is well-known in the industry for starting its employees at wages higher than the federal minimum. According to the salary information shared with Glassdoor by Costco employees, the average starting wage for cashiers and stockers is $10 per hour, with the opportunity to earn more than $20.

In addition, Costco offers a comprehensive insurance, disability, and employee stock purchase benefits package to all its workers, including part-timers after six months on the job, with coverage options for children, spouses, and partners. "For people who have no desire to get a degree or a trade, Costco offers great salary and all the benefits you need for yourself and your family," wrote a Costco tire installer from Fort Worth, Texas.

A chance to advance

Even at a company that offers a good starting wage, the thought of doing the same job for years on end could leave anyone discouraged. That may be why so many of the companies that made the list earned raves from workers for the chance to move up, take on new responsibilities, and earn more money.

Competing home-improvement chains Lowe's (NYSE:LOW) and The Home Depot (NYSE:HD) ranked No. 9 and No. 10, respectively, based, in part, on positive employee feedback about advancement opportunities. A Home Depot customer order specialist in California rated her employer highly because "there always seems to be opportunity here." At a Lowe's in New York State, one store manager wrote, "I have been encouraged to grow with the company, with really no limit to the position I can attain."

Training for career gains

Advanced degrees and continuing education are well-known tickets to career advancement, but the cost and extra time involved place MBAs, software certifications, and other credentials out of reach of some workers. Companies that provide training in-house can earn loyalty from workers who are eager to add to their skill sets.

Chipotle Mexican Grill (NYSE:CMG) and Apple (NASDAQ:AAPL) workers made a point of mentioning company training in their reviews. "They... offer a lot of opportunities for employees to get training toward roles/positions they're interested in," wrote an Apple Family Room specialist in Palo Alto, Calif. A Chipotle front-of-house team leader in Connecticut recommended the company because "they have a great training plan that helps you to feel confident in your position."

Beyond the hourly wage

It's clear from the reviews left by workers that they're willing to accept a low wage to begin with if their work leads to opportunities to earn more, and advance within the company. In-house training programs can take some of the financial and time stress off employees, while helping them become more valuable to the team, and the benefits like good health insurance appeal to workers of all educational backgrounds. Anyone looking for a decent job that doesn't call for a college degree -- and any company seeking to attract and retain workers -- would do well to study the companies on this list.

John Mackey, co-CEO of Whole Foods Market, is a member of The Motley Fool’s board of directors. Casey Kelly-Barton has no position in any stocks mentioned. The Motley Fool recommends Apple, Chipotle Mexican Grill, Costco Wholesale, Home Depot, Starbucks, Wells Fargo, and Whole Foods Market. The Motley Fool owns shares of Apple, Chipotle Mexican Grill, Costco Wholesale, Starbucks, Wells Fargo, and Whole Foods Market. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.