Nominal tax rates were 70 or 90 per cent, but no one really paid them. The tax code was full of loopholes for that purpose.
You can't rely on such paper figures to determine real tax burden in the past.
Which is still the case. No one is skipping getting rich because of taxes, they end up paying very little anyway.
What makes you think anything has changed here? Certainly in the UK, there are plenty of "loopholes". Outside of PAYE, there are plenty of ways to legally lower your tax burden, and plenty of wealthy business owners and shareholders make full use of those loopholes.
This is true and I believe it doesn't make sense to compare tax burdens of the people who are already wealthy.
It makes sense to compare tax burdens of well-paid employees, a favorite cash cow of most governments. These are the people who sometimes start new businesses, and use their savings to do so.
And there is a meaningful difference to the volume of their savings if their top tax bracket is 30 per cent or 55 per cent.