Answer:
Per capita income only divides the nation's GDP by the number of people in the economy and so has a couple of problems. One of those problems is that a nation's GDP is not completely tangible which means that it cannot actually be shared by people in a country.
The other reason is that income in a country is not shared equally like per capita income posits. Some people get more than others which is why billionaires and millionaires exist.
These problems out together mean that GDP cannot be an efficient measure of economic development because so many people in the economy would not develop at the rate that GDP per capita is insinuating.