Not sure if selfish quite captures it. It's more practical consideration. I'll give you X, if everyone else is also giving you X. Otherwise, my X won't make any difference.
Looking at again: it's a variant of the prisoner's dilemma. If everyone moves, nobody is worse off. If you move on your own, you are worse off. If everyone else moves and you don't, you're best off.
Unsurprisingly, the dominant strategy is to write blog posts saying "we really ought to amend the taxation laws" :D
