It's just science, man. One beer is not getting 180lbs of male to 0.08%. Not gonna happen. If you test with 20 minutes or so, you'll get a false reading

https://www.utoledo.edu/studentaffairs/counseling/selfhelp/substanceuse/bac.html#:~:text=It%20is%20calculated%20in%20grams,alcohol%20is%202%2C100%3A1).