Trust is also not freely available in developing or poorer countries, so being able to see and hold something is more important. In the US, the incidence of theft* is so low that you can trust your electronic accounts won't be emptied, and if they are, you have a court/regulatory system that will make you whole. This is an important asset for developed countries to have as it greatly reduces transaction costs, whereas in developing countries, people have to deal with worrying about what happens if they get on the wrong side of someone who has influence.

*Ignoring the constant devaluation of money to prop up asset prices.