But why not? When the coal miners went on strike they didn't suffer in any other way than to lose money (and, of course, lost friendships/broken families etc, but I'm talking about company inflicted penalties).
When posties go on strike, they lose the same.
Nobody else (from businesses of another nature) who goes on strike loses anything other than the cash they'd have earned had they been at work.
Walsh has honed in on this benefit we all enjoy and is using it as a bargaining tool when, to be honest, a lot of people aren't sure he should be. A lot of people would argue that staff travel should never have become involved in this whole dispute.