You don't need expert lobbying. Look at this forum, full of tax-evasion apologists who conflate pragmatism with pedantry.
Pedantry is the one of the most intellectually and emotionally bankrupt moral frameworks. It basically states that if you just think about the rules a lot, then you will find the solution.
I mean, obviously all these politicians and normal people, they've just been getting it wrong all along! To quote other commenters, "Apple did nothing illegal!" The "Tax law is a system of rules!" Just look more carefully at those random tiny rules and then, we don't have to have a discussion anymore! People who don't read the rules carefully enough: "it makes my brain hurt!" Then blame the people who write the rules, or petition for the rules.
Pedantry is the disease, not lobbyists.
I don't know how to convince the pedants though that sometimes, it's ethical to reinterpret the rules.
To clarify, I think we should be asking whether or not what Apple does is ethical. And the answer to that question shouldn't depend on whether or not we're wondering the same about other corporations.
The answer is obviously no, tax evasion / avoidance isn't ethical.