system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:  Why does the department of Alcohol, Tobacco, and Firearms exist.  What do these things have in common?
gpt
ATF started out as an enforcement division of the IRS; it was responsible for those things because those things have special taxes applied to them. It was spun off in the 70s, and since the Homeland Security act it hasn't even been responsible for the taxes, but the history remains.