I just recall this from when I used to enjoy alcohol - ordering a martini to test proficiency of bartender, and then getting charged for a full, disgusting entire shot of vermouth in there because the bartenders get in TROUBLE for not metering out shots in full, across many bars. Like there's just no recourse for them to add a little capful because there's graduated marks on the bottles and their boss is being overbearing, across many different bars this being the policy.