system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it legal to drink 1 beer and THEN drive, but illegal to drink 1 beer WHILE driving?

I understand that you aren't "allowed" to drink beer while driving due to the "open container" law, but what is the reasoning behind this?  You'd have just as much alcohol in your system either way.
gpt
I always figured it was because it's not very practical to pull someone over and ask,"Is that your first beer? Okay good, just checking. Have a nice day."

Easiest way to enforce that law is to have a 0 tolerance policy on open containers/drinking & driving.