IRC is not shareware. It is a large number of networks following a given protocol for communication. It is in essence, no different than IM. Yes, it isn't the same thing, but it's still the same type of thing. Just like IM isn't shareware, neither is IRC. Some software, such as mIRC, is shareware however.
Now... Verizon has stated in the past that they block IRC networks that are deemed "bad". Trying to connect to a network like Efnet is probably not going to happen over Verizon unless you're lucky. The reason is that a lot of spammers and flooders are on the network and causing a lot of wasted bandwidth that Verizon does not want to deal with (pay for). So they do block some IRC networks, but not IRC in general. Even so, it can be difficult to connect to IRC with Verizon depending where you live. I can use IRC on my Verizon cellphone, but I can't connect every time... only around 35% of the time.
There are times when you can get in touch with the right person at an ISP and they can get things working for you that are normally either purposely not allowed or just simply aren't set up and they don't want to set them up. But much of the time, no matter what ISP you have (at least among larger ISPs), you aren't going to have much luck getting them to fix the problem.
In the end, the ISP isn't required to let you use any given network protocol (IRC, IM, P2P, etc) if they don't want to. Some laws have tried to prevent ISPs from discriminating certain protocols with only limited success. Others have given more power to the ISPs to do whatever they want. The best thing those who want free use of all protocols can do is to bug your representatives to put forward and vote for bills to provide open internet. It probably won't happen without enough people bugging their representatives across the country... or, in other words, it probably won't ever happen. *shrug*