The problem is that no one actually paid that, during that same time period tax avoidance was stupidly easy. The average tax rate for the highest earners (over 200k) rarely paid over 45%. Still higher than the average of today, but nowhere near what most people claim about the time.
Plus, before 1986 a lot of the really rich people who could afford to lobby politicians used to be able to create "riffle-shot provisions" basically highly personalized tax carve outs created for them by individual politicians.
The most famous individual tax carveout in American history occurred in the Revenue Act of 1951. Louis B. Mayer, the mega-wealthy head of Hollywood studio Metro-Goldwyn-Mayer (MGM), wanted to retire and cash out his massive share of the studio's future profits. Under normal rules, this lump sum would be taxed as personal income at a whopping 91% rate.
Mayer hired a powerful Washington lobbyist who worked with standard-setting politicians to write a highly specific amendment. The law stated that a taxpayer could treat a retirement payout as a lower-taxed capital gains distribution (taxed at only 25%), but only if:
• The taxpayer had been employed by the company for more than 20 years.
• They had held a contractual right to a share of future profits for at least 12 years.
• They had been entitled to these rights for at least 5 years after termination of employment.
• The entire payout occurred in a single block in one tax year.
The criteria were so incredibly specific that Louis B. Mayer and one other MGM executive were the only two people in the United States who qualified. It saved Mayer an estimated $2 million ($23+ million in today's money).