I wouldn’t be so quick to dismiss the impact that taxes can play. A player is Dallas takes more money home, on an after tax basis then a player in Vancouver does. Means that Dallas can sign a player for quite a bit less than Vancouver can and the player ends up taking home the same amount on an after tax basis.
This makes it a lot easier to construct a superior team in a salary cap league.
Also, in the competition to sign free agents, Dallas has a better chance then Vancouver does because of the tax differential.
There are a lot of other considerations that impact a player’s decision about where to play, and not all teams try to build their team through free agency. Having said that, tax does have an effect. The question is, how important is that effect on the over all scheme of things. IMO it is somewhat important.