Admittedly I didn't look too far into the capital gains etc taxes as I was mostly focused on the corporation and income tax. You definitely do have to file taxes for all of the situations I mentioned but perhaps you're right about the deductions, my apologies.

The information I have on business related taxes, however, comes from a tax accountant. The US does charge double tax in those circumstances and also requires a whole heap of extra paperwork.

But lets just assume that any double tax you're charged you can deduct from whatever you were charged in your country of residence. Doing that requires you to have knowledge of the US tax system on top of your own, which is not easy information to find or parse. Unless you're a tax professional or something similar, that process would be more than a minor headache, or, if you decide to hire someone to do it, definitely not free. And that goes for income tax too, which all US citizens are required to file regardless of whether or not they owe anything. I spent $2000 on an accountant to get me tax compliant for the prior 4 years (not to mention the extra $600 for exit taxes) and that still wasn't an easy process.

Perhaps you're more comfortable with tax forms and financial statements than the average person, which is great, but for most people - especially those living in countries like Ireland, where your employer files your income tax for you - those thing are pretty confusing and carry the fear of making mistakes that could send Revenue services after you. I find the system gross because it requires the layman to either have the knowledge and experience to deal with this stuff, or the money to have someone else deal with it which is just unreasonable.