Our company hires some FAE/sales in China.

Their salaries are almost the same as US employee. 

BTW your number for 30 years ago is not right. 30 years ago, 1983, an engineer in China earned at most 100 yuan a month. An engineer in US could make about $3000 a month. The yuan/dollar change rate was about 2 (officially), but you can exchange about $40. You can get the black-market rate at about 6-7 (?). So you earned about 200 times as your old coworkers.