If you lose money on investments, you typically won't be liable for taxes - so yes, risk taking
does get incentivized. Only
gains are taxed, and in progressive tax brackets. (You can also carry losses forward, which too incentivizes risk taking over fixed income generation.)
Contrast this with a 30% flat tax on
revenue in Apple-land, which you have to pay to Apple even if your app is unprofitable.
The right to earn money on the very lucrative U.S. market is taxed
very favorably compared to the right to earn money on the Apple market.
The "U.S. government" in this case is simply the representative agent of the owner-shareholders of the U.S. market. Owner-shareholders are all U.S. citizens, who each got a single non-transferrable voting share at birth, and who can change the tax system with a majority vote.
Why shouldn't shareholders have the right to ask for fair fees and profit sharing to access a very lucrative market they own? In fact your anti-taxation argument is weirdly anti-capitalist and communistic...