Labor is usually helpless against capital. The employer, perhaps, decides to shut up the shops; he ceases to make profits for a short time. There is no change in his habits, food, clothing, pleasures—no agonizing fear of want. Andrew Carnegie
Back when companies were far more solvent than today, labor's ability to strike was balanced by capital's ability to lock-out (i.e. close down operations). Call it an artifact of solvency.
These days, while labor is deemed to be on the ropes by many, it is capital which, by virtue of the increasing web of necessary payments to the financial sector which seems to me to be on the ropes. Capital can't lock labor out, it is beholden to finance (as finance is to itself) in much the same way men of Carnegie's day were beholden to capital.
I'll be a most interested observer of the Greek strike. I wonder how many days it will be before the banks cry "no mas" and labor discovers it has newfound power. It's all about sufficient reserves, and it's easier to stock-pile food for a week than it is to stock-pile sufficient payments to the financial sector in the event of a business shut-down.