Isn't the stupid thing that the tax system is set up such that these things are possible(to pay less tax than you 'should')? As David Mitchell says[0], making how much tax you pay a sliding scale based on your morality or ethics(while still remaining on the right side of the law) is just a tax on morality and ethics - the people with the least of those things will end up richer than the people with more of it, which is 'fucking bonkers'
I got into a big argument over a Monopoly game once - three of us were playing, Player 1 was in the clear lead, I was in second place but at a large disadvantage, and Player 3 had the least assets but was not having fun and wanted to leave the game. The rules of monopoly say that a player quitting gets all their properties sent to the bank, which then auctions them off. If that happened, Player 1 would have easily beat me in a heads up manner. So I convinced Player 3 to not quit just yet, and to sell me all of his properties for $1. Player 1 was furious, saying it was against the rules, but there is no rule against selling your properties for next to nothing and then quitting immediately. Was I in the wrong for convincing Player 3 to sell me his properties before quitting?
FWIW, that's not against the rules, you can have custom 'contracts' like that; iirc it's even so allowed that there's a stipulation for when it may happen (the beginning of the instigator's turn, I think) in the rules.
I think (I think) the answer is that it's not really about morality or ethics, but about finding an equilibrium between desired taxation and profit optimisation. The latter finds ways to reduce tax burden, and if that results in an unacceptably low burden the former (should) responds with rule changes.
But that points to it being more political than ethical, that's perhaps quite a free-market capitalist take on it.
I got into a big argument over a Monopoly game once - three of us were playing, Player 1 was in the clear lead, I was in second place but at a large disadvantage, and Player 3 had the least assets but was not having fun and wanted to leave the game. The rules of monopoly say that a player quitting gets all their properties sent to the bank, which then auctions them off. If that happened, Player 1 would have easily beat me in a heads up manner. So I convinced Player 3 to not quit just yet, and to sell me all of his properties for $1. Player 1 was furious, saying it was against the rules, but there is no rule against selling your properties for next to nothing and then quitting immediately. Was I in the wrong for convincing Player 3 to sell me his properties before quitting?
BTW, I ended up winning the game.
[0] https://www.youtube.com/watch?v=m2q-Csk-ktc