There are finite financial resources, material resources, and Human Resources to address issues in society. Additionally, there is only so much mental capacity people can take to focus on topics to address both on the administrative side and the public side. The more you widen your focus in a given genre (this case an umbrella of drugs), the less actual good you'll be able to do.
Also, depending on your state, they aren't really "on" the issue. In my state for example, it is illegal to prosecute drug use if the police are there for a medical call. You can literally be surrounded by drugs and paraphernalia and police can't do anything beyond handing a flyer to get help. They don't even take the drugs!
You can OD on fentanyl, get your nasal spray to get you out of it, decline transport to the hospital after your onsite medical examination and everyone just goes home. You can then do it all over again as soon as you want. To me, it seems to make more sense to allocate more of your finite resources to a more urgent issue than tobacco in the larger scheme of drug control.