It's interesting to observe the process of bartenders or club bouncers in USA verifying foreign driver licenses, esp. if someone looks like they are in their 30

It's interesting to observe the process of bartenders or club bouncers in USA verifying foreign driver licenses, esp. if someone looks like they are in their 30s or older. A person turns the driver license around a few times, too quick to read anything on it and gives it back to you, or they ask you where the birth date is and quickly check whether the four-digit number you pointed them to is smaller than whatever the current cut-off date is.