OK let's say you have the option to work for two different companies. You have no preference for either and they offer the same benefits and perks. But, you will make 7.5% more if you work for one of the company. Which would you choose?
You're missing an important point.
7.5% is a lot if you're talking in the 30k range. That extra 2k a year is huge because you're on a budget.
But with 3M? The extra 200k will be sitting in your bank account and you won't see the difference.
As I wrote previously, coming from the mouth of a guy who went to multiple NHL teams, it rarely is a concern for players.
I'm sure most players want to play for a good organization, in a nice city, get good money and term etc. If taxes was THE factor, Edmonton would be one of the most attractive places for UFA...