2) If the US taxes in 1950s were lower, it indeed would make US an even more attractive place for capital. However, the US was going through an industrial boom because of variety of other factors then, unlike any other country in the world. Now, situation both in US and other countries is quite different, and tax factor is more important.

Basically, when you have the best goods on the market, it's OK to ask high prices, but when you get competition, it's not such a wise move to keep them high.