Serving alcohol as part of a job years ago, I was required to keep a tab on how much alcohol was served to each patron as the restaurant was legally liable the minute the beer or wine touched the lips of the patron.  Our manager was very careful to limit how much alcohol was served to each table to the extent that if only 1-2 people were at the table, they were only allowed one glass of beer or wine within one hour.  If a table had three or more people, the manager would allow one pitcher of beer or one bottle of wine during the said hour, and we were required to watch who drank it.  So, yes, restaurant, bars, taverns, and servers do keep an tabs on how much alcohol is consumed and by whom; maybe, not all establishments or servers do, but since both the establishment and the server are legally liable for any accident resulting from too much alcohol consumption, I would tend to think most businesses and servers are responsible in the serving of alcohol.