Every time someone tries to make a tax targeting the ultra rich, it ends up hurting the moderately wealthy instead. Every. Single. Time. The worse tax situation is always the person who makes 500k in a good year, or sells a house they held for 25 years which went up a bunch in value. I suspect this is a significant factor in social mobility. Our tax system is punitive to people who try to leave the working class.
I don't think you're describing an obstacle to change, you're describing the mechanism of change avoidance. Compare: "Gosh, every time we try to tax the wolves, it ends up hurting the sheep as well. Why can't our 100% wolf, 0% sheep Congress get this right? I guess it's just a hard problem!" The solution is not to give up, the solution is to actually tax the rich more. Also, your examples are awful: paying taxes on t…
Raising the top rate on income when most of the ultra-rich's money comes from investment isn't making sense. There is also little interest in creating ultra-high tax brackets. I agree in principle with someone earning $5 million/year paying a higher percentage than someone earning $1 million/year. Many countries the top rate starts at $120,000ish in local currency.
Taxes on the sale of a primary home is not as rare as you think. It may be a twice in a lifetime event for many people but if it costs you a fortune each time people are discouraged from buying starter homes and then upgrading as their family grows. Make this too expensive and people even choose to have fewer children rather than get a bigger house. People may also choose to avoid the real estate market early to wait for a realistic home and risk getting priced out entirely. Admittedly, capital gains taxes are less punitive than land transfer taxes in this regard but it's still a factor. A capped to $500K of capital gains on a primary residence of tax avoidance is useful for middle and upper middle class Americans. It's not a measure designed predominantly for the rich unless your definition of rich is so broad that it includes any property owner. We've seen what happens when you create markets where people can't move and it looks a lot like San Francisco. That's not something I'd want policies to try and replicate.