People factor this in all the time. It's reality when considering a new job or retirement. You often see articles on the tax implications of living somewhere and it's factored in to many of the "most livable city" lists.

And even though it's usually illegal not to report it on a tax return, people cross state lines a lot for purchases (cigarettes, alcohol, electronics). Portland for instance has no sales tax while its very close neighbor Washington has no income tax.

This could all play out with Internet taxes too.