The term "livable wage" is very nebulous.
That may be one excuse. It's misguided though, because if Walmart paid every employee $6k/year more than they currently do, then they'd have no profits.
It would not necessarily be that they would not have profits per say however the added costs would be shifted elsewhere in their business, i.e. higher prices, reduce benefits, etc. Of which if prices climb that would put Wal-Mart in competition with stores like Target or Costco who do not actively seek to provide goods and services for the bottom half of the US. Additionally the decrease in ROI on some stores via higher prices would mean that increased worker costs would see some of these stores shut down or not open at all in some areas.
Additionally I agree that the term a "living wage" is indeed a distorted term. Its used to cloud up the conversation for the lack of job creation of skilled jobs in the marketplace by insinuating that no-low skill jobs are on par with jobs which require actual skilled and/or academic knowledge to justify their higher wages.
As for the OP:
Does a ditch digging job or working at McDonalds mean you should earn enough to raise a family? Are these the types of jobs we are reduce to promoting? If so then this economy is in a sad state of affairs despite the cherry picked commentary that the economy is "on the mend".
Additionally raising wages for such low skilled jobs inevitably means you push out people who once could attain these jobs without having to provide too much in the way of qualifications. Furthermore you'd also see a drastic reduction in the amount of job listings for these types of jobs in the marketplace as employers seek to do without the added costs of hiring another employee at a higher wage rate.
So suddenly you'll have more and more people competing for these jobs at a higher wage rate if and when they come onto the marketplace due to these jobs now being more costly for the employer to fill. Which also means employers will be forced to find alternative methods to sift through the glut of potential workers and again that means these jobs which were once plentiful (as most people did not view these jobs as being able to raise a family on in the past but now they do via higher wages) for certain groups of people in society will now become off limits for them as competition for those jobs heats up.
So in the end people who espouse a "living wage" for unskilled or low skilled jobs are doing a horrible disservice to future unskilled or low skilled workers because as I stated above, once these jobs start to pay more in that you can actually raise a family on the wages the competition heats up for these jobs. So people with significantly more job skills or experience will be the first in-line to be considered for these types of jobs. Additionally these jobs will also start to dry up as employer costs rise and again more and more people compete for these jobs.
So if the goal is to push minority, teen and elderly unemployment rates higher well by all means go right ahead and provide a "living wage". However if this is not the actual goal then maybe people might want to stop and think about what exactly they are demanding when they push the term "living wage" for a burger flipping job and also stop think about how significant wage increases (i.e., "living wage" so as to be able to raise a family on while working a no-low skill job) will play out for these businesses who provide these types of jobs that literally can be filled by anyone off the street and additionally what job market for these jobs will look like in the long term.