Before the UK introduced a minimum wage in 1997 the business community offered grave warnings of job losses. This never happened. Perhaps companies were more able to absorb the costs than they claimed, perhaps the increased spending power brought about by the increase in wages helped companies to increase their revenue and pay the increase in wages. What it did mean was that taxpayers and the companies that already paid what the government eventually decided was a fair wage no longer had to subsidise those that didn't.
As for the assertion that 'playing with the laws of supply/demand is a bad idea', I've got to say that supply and demand should only be taken so far. When market forces determine whether a working person has access to food, shelter, healthcare and education then we've lost our humanity. On that note, please visit
makepovertyhistory.org.
Anyway, are the wages companies pay really a simple result of supply and demand?
"Wal-Mart is more than just a participant in the low-wage economy: It is the most important single beneficiary of that economy.
It uses its economic and political power to extend the scope of the low-wage economy and threatens to extend its business model into other sectors of the economy, undermining the wages of still more workers."
http://www.inthesetimes.com/site/main/article/717/P80/
The article's very biased but the threat to everybody's salary of a low wage economy populated by powerful corporations is real.