Sources of data for GDP and BoP accounts When an American buys a coffee within the US, how does that 3.50 dollars worth of consumption expenditure make it's way to the US GDP account? Is the information obtained from the company's tax records? When a French citizen buys the same 3.50 dollar coffee in the US how does that information get reported so as to make it into the US and French Balance of Statements? I don't see coffee shops asking customers for passports when these order coffee so how does the coffee shop know how much it sold to whom? How does the French government get information about this coffee purchase by one of its citizens in the US to know to reflect it on its Balance of Payments statement?
When an American buys a coffee within the US, how does that 3.50 dollars worth of consumption expenditure make it's way to the US GDP account? 

It would be personal consumption expenditures which primary data source is from the: 

BEA’s Benchmark Input-Output (IO) Accounts, which are based primarily on the Census Bureau’s Economic Censuses

BEA’s International Transactions Accounts;

Census Bureau’s Annual Retail Trade Surveys

Service Annual Surveys 

Quarterly Services Surveys

Monthly Retail Trade Surveys  (the coffee purchase would most likely come from here)

Bureau of Labor Statistics’ Consumer Price Indexes

https://www.bea.gov/sites/default/files/methodologies/nipa-handbook-all-chapters.pdf#page=90   page 5-7

When a French citizen buys the same 3.50 dollar coffee in the US how does that information get reported so as to make it into the US and French Balance of Statements?

This questions seems to be difficult to answer; however, after looking at the BEA’s Balance of Payments methodology on data sources it seems that this information is easily collected  from the BEA’s Quarterly Survey of Payment Card and Bank Card Transactions Related to International Travel (BE–150) 

[As long as they are paying with a credit/debit card].  

(https://www.bea.gov/sites/default/files/methodologies/ONE%20PDF%20-%20IEA%20Concepts%20Methods.pdf#page=8)  [page 13-5] (section 13.23)

This survey is filed by U.S. companies that operate payment and bank card networks. The survey captures information on credit, debit, charge, automated teller machine, and point of sale transactions between U.S. merchants and customers holding foreign-issued cards and between foreign merchants and customers holding U.S.-issued cards.

When a French citized buys the same 3.50 dollar coffee this transaction would be collected (if the person uses a credit or debit card) by the persons bank card company.  Then the bank card company would fill out the survey and indicate that their card user bought coffee at a US firm for 3.50 dollars. 

This information would be submitted into the mandatory survey that the BEA collects for their balance of payments direct investment (chapter 13 of BEA BOP methodology).  https://apps.bea.gov/itable/itable.cfm?reqid=62&amp;step=1