1) Seeking &quot;tax shelters&quot; through investment. Very inefficient, however.<p>2) Factors other than the tax system. Correlation != causation, IOW. The U.S. had (something approximating) the only standing industrial infrastructure in the world post-WWII. It&#x27;s also worth noting that the Kennedy tax cuts probably released a lot of pent-up economic energy. Similar tax cuts under different circumstances may not have the same effect - there had been widespread privaiton in the US from 1929 until the &#x27;50s, and this sort of acted as a &quot;second stage&quot; booster.<p>3) A general cultural civic-mindedness. I recently listened to a presentation of Devon Energy&#x27;s CEO, and his father started a fund in energy and wanted it structred as a registered security , one of the first , and was told &quot;you don&#x27;t need to do that&quot; by the SEC, but he persisted because he felt that was better.<p>He then contrasted that now with people spending lots of money to avoid SEC regulation. That highlights the level of culture shift since then.