I think the difference, from the perspective of the regulator, is that a firearm is a tool with a limited scope of use, and that certain firearms (pistols) have a further limited scope of use that makes their existence noxious. In the US, the 2nd amendment makes this a controversial issue -- not so in most other jurisdictions.
Possession of burglary tools or drug paraphernalia is typically a modifier used to punish ill-intent. If I'm a carpenter walking home from work with a saw and hammer in my bag, I'm not going to be arrested for possessing burglar tools. If I'm trespassing on someone's property in the middle of the night with a crowbar, on the other hand, I'll probably be prosecuted for possessing burglar tools.
"Hacker tools" is sort of in the middle. A sysadmin with metasploit on his laptop is no different than a carpenter with his hammer. The Level-1 helpdesk technician pinched for stealing passwords is using it as a tool for doing "bad" things. The complication is that the line between "hacker tool" and "legitimate" software is thin or even overlapping.
So why criminalize possession if possession will only ever be prosecuted in the context of some other crime? If prosecutors or legislators think they need longer punishments for those crimes, why not just extend the sentence for the base crime, rather than tacking on a bunch of technical crimes like "possession of things we don't like"?
I think that the legal theory is that possession of certain items is indicative of bad intent.
If I carry x quantity of illegal drugs, I'm a user getting charged with a misdemeanor. If I carry x + y quantity of illegal drugs, I'm presumed to be a drug dealer.
I'm just explaining the thought process -- not agreeing with it. Unlike drug sales or burglary, the most important tool for hacking is whatever is in your head.
Possession of burglary tools or drug paraphernalia is typically a modifier used to punish ill-intent. If I'm a carpenter walking home from work with a saw and hammer in my bag, I'm not going to be arrested for possessing burglar tools. If I'm trespassing on someone's property in the middle of the night with a crowbar, on the other hand, I'll probably be prosecuted for possessing burglar tools.
"Hacker tools" is sort of in the middle. A sysadmin with metasploit on his laptop is no different than a carpenter with his hammer. The Level-1 helpdesk technician pinched for stealing passwords is using it as a tool for doing "bad" things. The complication is that the line between "hacker tool" and "legitimate" software is thin or even overlapping.