Shock current path page

Hi I had a question about one of the grounded circuits (The circuit with the 2 people separated by the resistor and the tree touching the top wire) Shock current path page

-top person is safe and bottom person gets shocked

My question is why doesnt the current flow threw the two people and shock both of them instead of flowing threw the tree and the person at the bottom. There is a voltage difference between both people due to the resistor. How is this different then the voltage difference between the person on the bottom wire and the tree due to the power source?

Any feedback will be much appreciated thanks.